Residential Testing FAQs


I want to make sure my water is safe, what tests should I request?

I just generally would like to make sure there are no contaminants in my water.  Where’s a good place to start?

A good starting point would be to test for Nitrates, Nitrites, Turbidity, and Bacteria. You may also want to test for Hardness.

I am pregnant, or have small children. Is there anything I need to make sure I test my water for?

Yes. Test for nitrates because elevated nitrate levels usually do not cause a problem for healthy adults, but can interfere with the transport of oxygen in the blood of small infants or unborn children, which can lead to a condition called methemoglobenia (blue baby syndrome). Also test for lead, because infants are most susceptible to lead toxicity, and test for bacteria because again, infants are more susceptible to infection by bacteria because they do not yet have fully developed immune systems.

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I think there’s something wrong with my water, what tests should I have done?

What could be wrong with my water if…..

….my water smells like sulfur, or rotten eggs?

If you notice this smell in your water, it probably contains hydrogen sulfide (H2S) gas. Reasons for this may include:

  • Decay of organic matter or reactions with minerals present in soil and rock that contain sulfur.
  • Sulfate-reducing bacteria which can convert naturally occurring sulfate into hydrogen sulfide gas
  • Water heaters, which provide a warm environment for sulfate-reducing bacteria to live.  The water heater also contains an annode which supplies electrons that can sustain the reaction of sulfate to hydrogen sulfide gas.

Should I worry about hydrogen sulfide gas or sulfur-reducing bacteria?

Sulfur-reducing bacteria not only produce hydrogen sulfide gas, but they also generate slime that can provide a good environment for other bacteria to grow in addition to clogging pipes in your plumbing system.

Hydrogen sulfide gas may cause black spots on silverware and plumbing fixtures and can corrode pipes.

How do I figure out where the hydrogen sulfide gas is coming from?

First run just the cold water, and note whether or not you notice the smell.  Then run the hot water and smell the water again.  If you have any water treatment systems, such as a water softener, make sure to smell the water with the treatment system on and also with it disconnected.

  • If you notice the smell only when the hot water is running, the problem is probably your water heater.
  • If you notice the smell in both the hot and cold water, but only when the water softener is on, you may have sulfur-reducing bacteria in your treatment system.
  • If you notice the smell in both the hot and cold water but the smell diminishes the longer you run the water, you may have sulfur-reducing bacteria in your well or plumbing.
  • If you notice the smell in both the hot and cold water and the smell does not diminish as the water runs, you may have hydrogen sulfide gas in your well or ground water.

What can I do to get rid of hydrogen sulfide gas?

  • If the source has been determined to be your water heater, remove or replace the magnesium anode, then disinfect and flush the water heater with a bleach solution. Increase the water temperature to 160 degrees Fahrenheit for several hours to kill the bacteria, then flush the heater.  If you do not feel confident with heater maintenance, contact a water heater dealer or a plumber to perform this service.
  • If the source has been determined to be sulfur-reducing bacteria in the well or plumbing, disinfect the well.  For instructions on how to disinfect your well by chlorination, see My water has bacteria in it, how do I go about chlorinating my well?
  • If the source has been determined to be sulfur-reducing bacteria in the water softener or treatment unit, contact the manufacturer for instructions on how to disinfect the unit.
  • If the source has been determined to be hydrogen sulfide in the ground water, you may use activated carbon filters for hydrogen sulfide concentrations of less than 1 milligram per liter (mg/L).  If your levels are higher than 1 mg/L but lower than 6 mg/L, you will need to use manganese greensand filters.  If your levels are higher than 6 mg/L you will need to install an oxidation filtration system.

If your water smells like rotten eggs, you should test for bacteria, sulfide and sulfates.

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….my water is cloudy?

If the problem is worse after rain, it is probably sediment and indicates an intrusion of surface water into the well. A sudden appearance of cloudiness may indicate the collapse of the well wall.

If your water is cloudy, you should test for bacteria and turbidity.  

….my water produces brown stains?

Brown stains usually indicate the presence of iron or manganese in the water.

If your water produces brown stains, you should test for metals.

….my sinks have blue/green stains in them?

Blue/green stains indicate that acidic/corrosive water is passing through copper pipes and dissolving copper from the pipes and redepositing it as copper sulfate on the plumbing fixtures. This problem should be addressed, because pinpoint leaks can eventually develop in the system as a result of this leaching process. It also increases the possibility of leaching lead from any lead solder joints or lead-containing fixtures. The problem can be fixed with an acid neutralizer.

If you have blue/green stains in your sinks, test for acidity and pH.

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….my water has an iridescent film floating on top of it?

An iridescent film (a thin, colorful sheen) floating on top of water can mean one of several things. The first thing most people would assume is that the film is caused by oil or other petroleum products in the water, which may very well be, but that isn’t always the case. When certain iron-containing minerals (for example hematite or limonite) are present in water that has a lot of organic matter in it, the minerals dissolve. However when the dissolved minerals come into contact with air at the surface of the water, they can react (oxidize) and mix with un-dissolved iron ions to form the sheen you see on the water. Iron oxide films are naturally occurring and generally do not indicate a problem, however the presence of an oil sheen on the water can indicate a leaking underground storage tank, or some other source of contamination that could be affecting other water sources in the area. One way to tell the difference is to take a stick and stir up the water. If the film breaks into pieces, then it is most likely an iron oxide film. If the film merely swirls around but remains intact, then the film is most likely caused by oil.

Fredericktowne Labs can perform iron, manganese, and TPH DRO and GRO (Total Petroleum Hydrocarbons, Diesel Range Organics and Gasoline Range Organics) tests to help you figure out what is causing the film and advise you of what steps to take once you have your results.

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I think I might have gasoline or fuel in my water. How did it get there, and what should I test for?

Over the past fifty years, many buried gasoline tanks have been abandoned or not properly monitored and are now leaking gasoline into the environment. Unfortunately, once gasoline or fuel oil is lost from the tank into the environment it can travel through the ground for long distances and can cause well water problems for many years. It is very important that underground tanks not be abandoned with product in them since they will invariably corrode through and contaminate wells.

For suspected gasoline contamination, you should test for BTEX which stands for Benzene, Toluene, Ethylbenzene, and Xylene. These compounds are major components of gasoline.

Other compounds recommended for testing in addition to BTEX are MTBE and Napthalene. MTBE stands for Methyl tertiary butyl ether. This compound is a gasoline additive (octane enhancer). Napthalene is a component present in fuel oil and is used to differentiate between gasoline and fuel oil contamination problems.

If you feel that your water supply is being contaminated by a leaking underground storage tank, you may want to contact the Maryland Department of the Environment, Leaking Underground Storage Tank Division, 1-800-633-6101, Ext. 3442.

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I’m buying or building a house, what do I need to know?

When should I test my well?

Test any new well that has just been drilled. After the contractor chlorinates the well and pumps the chlorine clear, allow the well to return to normal conditions for about a week. Then contact a lab for testing. Test your water before it is used for drinking.

Also test the well before you purchase a property, and test annually after that. The well may be clean now, but not necessarily forever.

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For what should I test?

Test for total and fecal coliform bacteria, and for nitrates.

For more information on wells and well construction, please see our tipsheet on wells.

I am concerned about radon, what do I need to know?

What is Radon?

Radon is a naturally occurring gas produced by the breakdown of uranium in soil, rock and water. It is the decay products of radon, called “radon daughters” that cause the hazards attributed to radon. These “daughters” are atoms of heavy metals and readily attach themselves to whatever they contact.

Can I see, taste, or smell radon?

NO. That is why people have a tendency to feel that their home is safe.

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Is radon harmful?

The surgeon General has warned that radon is the second leading cause of lung cancer in the United States; only smoking causes more lung cancer deaths.

How does radon enter the home?

Air pressure inside the home is usually lower than pressure in the soil around the home’s foundation. Because of this, your house acts like a vacuum, drawing radon in through foundation cracks and other openings.

Who should test for radon?

Everybody.  Everyone is susceptible to lung damage by radon, and there is no way of knowing whether or not you have a problem unless you test.

How is radon measured?

It is measured in picocuries per liter of air (pCi/L). Short term or canister method tests measure radon levels over a period fo 2-4 days. Long term tests such as Alpha Track measure an average value for a period of 2 months to a year. Continuous methods give hourly radon readings which are then usually averaged. Fredericktowne Labs is listed by the EPA as an approved laboratory for performing these tests.

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What level of radon is considered “safe”?

The EPA’s goal is that the indoor radon level be no more than the outdoor level, which is about 0.4 pCi/L; however, levels below 4.0 pCi/L are considered acceptable.

Should I take steps to repair my home if it tests higher than 4.0 pCi/L?

The EPA recommends fixing your home if the results of one long-term test or two short-term tests taken in the lowest lived-in-level of the home show radon levels of 4.0 pCi/L or higher. If you choose to do two short term measurements, it is advised that you perform the test during different seasons of the year.

If radon is found in my air, should I test my water?

It is a good idea to test your water as well if your radon in air test comes back with a level above the MCL.  Radon comes from the ground, as does your water, and corrective actions taken to reduce the amount of radon in your air will not help reduce the amount of radon in your water.

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I am concerned about my septic system, what do I need to know?

What is the current minimum requirement for septic inspections?

According to Maryland law, a septic inspection must include:

  1. A file search of governmental records to determine if the system was put in under permit, if there have been any modifications or repairs to the system, or if any problems with the system have been documented.
  2. An owner/tenant interview to find out and document what the residents know about the system and what their experience with the system has been (e.g., Is the system currently in use or, if not, how long has the residence been vacant? How many people are using it? Have they had any problems? Have they had the system pumped? Have they had any repairs performed? Were they done under permit?)
  3. An onsite field inspection of the system to include introducing water and fluorescent dye into the system, opening the tank, pumping out the contents, examining the tank for design, contents (scum, sludge, depth, etc.), integrity, and presence of baffles. The drainfield is evaluated for its ability to accept effluent properly (i.e., does not cause the tank to overfill and does not outbreak to the surface of the ground).
  4. Preparation of a report of findings that discusses and documents all of the above.

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Is a full inspection always necessary?

Some inspectors will perform a traditional visual or dye test if the buyer is willing to sign a paper stating that they understand the limitations of the test they have requested. This can make sense when the property has an old antiquated system and the buyers recognize that they will probably have to put in a new system and do not want to pay to hear what they already know. It can also make sense if the property is brand new with a new system that has just been installed under permit. In all other cases, it is highly recommended that the MDE protocol be followed.

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Why are septic inspections more expensive and involved than they used to be?

For many years the standard septic inspection that was performed for real estate transfer purposes consisted of a “visual” inspection of the ground surrounding a residence. Water was sometimes introduced into the system, sometimes not, and the inspector walked around the yard looking for any indications of “septic outbreak” such as unexplained wet spots, or telltale odor. If water from the house was introduced into the septic tank, sometimes a fluorescent dye was introduced at the same time, and the inspection was then called a “septic dye test”. Due to some large law suits and other pressure the Maryland Legislature in 1999 passed a Law: 9-217.1 that states “After July 1, 1999, every person engaged in the business of inspecting an on-site sewage disposal system for a transfer of property must certify to the Maryland Department of the Environment (MDE) that the person has completed a course of instruction, approved by the Department, in the proper inspection of on-site sewage disposal systems” This means that anyone who has not taken an approved course can not legally perform a septic inspection for real estate transfer purposes. The material presented in the course outlines very specifically what MDE considers to be the proper approach to conducting a septic inspection.

The type of inspection now required is much more time consuming and costly to perform than the traditional inspection done in the past. Many people are resistant to the idea of performing such a complex and costly inspection, however, the existence of the Maryland law makes it difficult to rationalize doing anything less. Should a problem arise with the system after the property transfers hands, the buyers would be within their right to question why an inspection that did not meet MDE recommendations had been performed when, by law, the inspector had been instructed in the “proper” inspection of septic systems. Should the problem result in a lawsuit, the inspector, the seller, and the real estate agent would all be vulnerable during litigation.

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When should more than that be done?

If you have reason to believe that something is wrong with your septic tank, it might be worth your while to have the septic inspector open up and check your distribution box in addition to the typical inspection.

For a diagram of a septic system and more info on maintaining a septic system, please see our septic tipsheet.

Is it really necessary to pump the tank?

In most cases, yes, it is always a good idea to pump the tank.  A septic tank should be pumped every 4 years.  Cases in which it is probably not necessary to pump a septic tank are:

  • If you are purchasing a property on which you know there is a very old septic system but you do not plan to use this septic system, you will probably just want to have the required inspection.
  • If you have just built or are purchasing a new house and you know the septic tank has barely been used yet, then it is not necessary to pump the tank during the inspection.

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I am concerned about lead, what do I need to know?

How great a threat is lead poisoning in the United States?

According to public health officials, lead is the number one environmental threat to children, whether they live in public housing or suburban homes.

What is the most prevalent source of lead?

A Newsweek article dated July 15, 1991 cites these statistics:

“74% of all private housing built before 1980 contains some lead paint.”

“3 million tons of old lead line the walls and fixtures of 57 million American homes.”

How does lead poisoning affect children?

Even small doses of lead can slow development and make children less intelligent.  Children with high lead levels are six times more likely to have reading disabilities and more likely to be considered hyperactive or aggressively antisocial.  Some studies have linked low-level exposure to hearing loss, slower reaction time, reduced attentiveness, delays in the age at which children first walk and problems with balance.

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How does lead enter a child’s body?

Peeling and flaking paint are often ingested by children who chew on painted furniture.  Fine paint dust stirred up by sanding or vacuuming during renovation may be inhaled or ingested by the child.  Friction from opening and closing windows can turn lead-based paint into lead dust which can then be ingested.

What treatment is available for lead poisoning?

A treatment called “chelation” uses injections to cleanse the blood of some lead.  This treatment is very painful.

Why is lead so toxic?

The body mistakes lead for calcium.  The lead attaches to and disrupts enzymes essential to the functioning of the brain and other cells.  Because it is an element, it never decomposes into another, more easily tolerated substance.  While it can be removed from the bloodstream through chelation, most of the lead that is absorbed into a child’s brain sits there literally forever.

What steps have been taken to deal with lead in paint?

Paint manufacturers removed much of the lead from paint in the 1950′s, but most of the paint remains in the same houses that got coats of this paint 40 or more years ago.

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What precautions can I take to avoid exposure to lead in paint?

  1. Before buying a house built before 1950, test for lead in paint.
  2. During renovations: If you have lead-based paint, the safest approach is to send children elsewhere until work has been completed and the house has been thoroughly cleaned.
  3. Hazards can be significantly reduced by replacing doors, windows and frames or by putting up wallpaper or paneling.

When should I test for lead in water?

Lead gets into drinking water by being leached out of the plumbing lines that the water travels through.  The water supplied by a community water supplier or by a private well seldom, if ever, contains lead.  It is the water supply lines that can introduce lead into your drinking water.  You should be concerned about the possibility that your water may contain lead if:

  • Your home or water system has lead pipes
  • Your home has copper pipes with lead solder joints, and you have acidic and/or very soft water.
  • You have faucets or pump fittings made of brass.
  • You have water pipes that were manufactured prior to the 1930′s
  • The home is less than five years old (pipes build up a protective coating over time).

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Can lead in water raise blood lead levels?

Yes. The EPA estimates that lead in water causes 10-20% of overall childhood lead exposure.  Young children and unborn babies are the most likely to be adversely affected.

Who should test my water for lead?

Any EPA-certified laboratory.  Fredericktowne Labs is certified and equipped to test your water for lead.  It is important that the sample tested is a “first draw” sample, which means it was taken after the water had been sitting for six to eighteen hours in the pipes, without any water being used in the house.  For more information on the first draw sampling technique and instructions on how to collect a lead sample, see Proper collection of a water sample for lead and copper analysis.

What is considered a safe lead level?

The EPA considers water acceptable for drinking if it has less than 15 parts per billion (ppb) of lead, although some doctors and advocacy groups call for levels of less than 10 ppb.

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What can I do if my water has an unacceptable lead level?

  • Reduce risk by running the faucet for a minute before using water.
  • When washing or cooking vegetables, use cold water which is less likely to pick up lead from pipes.
  • Consider installing an acid neutralizer if your water is too acidic.
  • Try to locate and have replaced any offending parts of the plumbing system.
  • If you have a water softener, consider getting rid of it.  A water softener can make matters worse since it will increase the corrosivity of the water
  • If all else fails, consider installing a filtering system that has been demonstrated to be effective at removing lead.  Check product information carefully.

Are there any types of containers that may contain lead?

Don’t store liquids that will be consumed in lead crystal.  If you wish to serve liquids from a lead crystal container, fill the container immediately before serving, and remove the liquid from the container afterward.  Also, be cautious about older glazed pottery, particularly pieces that were made in a foreign country.

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I have my test results, now what do they mean?

What do these abbreviations mean?

MCL stands for “Maximum Contaminant Level”. It is the highest level of a contaminant that is allowed in drinking water by the Environmental Protection  Agency (EPA).  It can be thought of as the level at which you might want to start thinking about taking some corrective actions with your water, because it could possibly affect elderly people, very young children, and people with compromised immune systems.

mg/L stands for milligrams per liter and is nearly synonymous with parts per million

ug/L stands for micrograms per liter and is nearly synonymous with pars per billion

< stands for “less than” and indicates that the component in question was not detected (i.e. was less than the detection limit)

Ntu stands for “Nephelometric Turbidity Units” and is a measure of how cloudy a sample of water is.

ppm stands for parts per million

ppb stands for parts per billion

C.U. stands for color units.  It is a unit of measure that denotes how much color is present in a sample.

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What does it mean if my well tests positive for nitrates?

Nitrates indicate sewage or fertilizer pollution.

My results say: “Bacteriological analysis of this sample indicates that the water is unsafe for human consumption….”  What does that really mean, and what should I do about it?

A failing bacteria test means that Coliform bacteria have been detected in the water. EPA has designated Coliform bacteria as the indicator organism for safe drinking water. What this means is that Coliform bacteria are pretty hardy bacteria, so if no Coliforms are found in the water, that implies that no other types of bacteria can survive in the water either. There are many pathogenic organisms (such as diphtheria, cholera, or polio) that could be present in contaminated water, but it would be difficult and costly to test for each one separately. Instead, environmental health labs test for coliform bacteria. If no coliform are found, the water has no other bacteria in it. If coliform bacteria are detected, then chances are good that there are other harmful bacteria present in the water. Unfortunately, about 25% of the wells in Frederick County are contaminated with Coliform bacteria.

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What causes a well to be contaminated?

The presence of Coliform bacteria in well water is frequently unsuspected because in and of themselves they seldom cause any noticeable health problems for the people who are accustomed to drinking the water. However, Coliform bacteria do not normally exist in well water that comes from a reasonably deep well (greater than 100 ft. deep). They require oxygen and organic matter (plant matter) to grow and therefore, while present all over the surface of the earth, do not normally exist in deep wells – no oxygen, no organic matter. Their presence in well water means that either the well is very shallow or something has happened / is happening that allows the well to be contaminated.

Any newly drilled well will be contaminated with Coliforms because the drilling process drags dirt down into the well. If a well is worked on (e.g. the well pump is replaced), the well will be contaminated with coliforms because the pump and the supply line will have been in contact with the ground before being inserted back into the well. If someone removes the well cap and throws a clod of dirt into the well, the well will be contaminated.

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What should I do about it?

All of the possible causes of contamination discussed above are one-time events and the usual response is to chlorinate the well by introducing Clorox or some other source of chlorine into the well. Chlorine is a very effective disinfectant and it will readily kill any bacteria that are present. (For instructions on how to chlorinate your well, see My water has bacteria in it, how do I go about chlorinating my well?)

Things become a little grayer when we encounter a well that is contaminated with coliforms but we don’t know why. Frequently, the answer is that there exists a well construction flaw that is permitting surface water to intrude into the well and contaminate the water, which would otherwise be pure. Well construction problems that can permit this to happen include:

  • Channeling down through the grouting (grout is the cement-like material that fills the space between the bore hole and the casing);
  • Casing which does not extend far enough down into the ground;
  • A crack in the casing;
  • Buried well cap (frequently not water-tight);
  • A flaw or leak in the pitless adapter (the compression fitting on the side of the casing just below the frost line that permits the water line to go from the inside of the casing to the outside of the casing).

For a diagram of a well with descriptions of the different parts, please see our tip sheet on Wells).

In cases like these, all the Clorox in the world will not fix the problem, except maybe temporarily. If possible, it is best to fix the well construction problem, chlorinate the well and test again. If the problem cannot be found or cannot be fixed, then the best solution is to install a permanent disinfection device such as an Ultraviolet (UV) light or a chlorinator. Either one is very effective at killing any bacteria that might be present. Most people prefer the UV light since it introduces nothing foreign into the water – the taste and odor of the water remain unchanged but the bacteria are killed. A chlorinator will, of course, result in water that tastes and smells of chlorine, like city water.

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My water has bacteria in it and I was advised to chlorinate my well.  How do I go about doing that?

The Frederick County Health Department supplies the following procedure for chlorinating a newly drilled well or a contaminated well:

  1. Before treatment, turn off the pump breaker at the electric panel box before removing the well cap to eliminate shock hazard.
  2. Remove well cap and electric wires from top of well. Make sure wire connectors are tight. Protect wire connectors with a plastic bag.
  3. Attach a garden hose to an outside faucet and place it into the top of the well casing.  For each 150 feet of well depth, add 10 oz. of Powder Shock which contains
    approximately 65% chlorine. Powder Shock can be purchased at most area pool retail stores. This powder should be added to 1 gallon of water, mixed and poured
    directly into well. Turn pump breaker on and circulate water from outside faucet into well. After chlorine smell is detected coming from the hose allow water to circulate into well for at least one hour. (Caution: This procedure may cause the water to become cloudy; however, it will clear up after the chlorine is run off.) Turn breaker off and replace wires into top of well casing. Replace and tighten well cap.
  4. Turn pump breaker on again and go into the house and circulate the chlorinated water through every fixture. (This includes toilets, sinks and washing machines). This should be done for at least three minutes at each site.
  5. Allow the chlorinated water in the water distribution system to sit undisturbed for a period of 12-24 hours. Run the chlorinated water from the distribution system
    through an outside hose avoiding the well and septic areas, as well as natural streams. Run the water for one half hour, then turn water off for an hour. Repeat this process until chlorine cannot be detected.
  6. If your well is a low-yielding well, or you are chlorinating during a drought season, you should avoid rushing the chlorine out of the system.

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How do I collect a water sample properly?

Proper collection of a water sample for bacterial analysis

  1. Select a glass or plastic container that will hold at least 1 (one) pint.  You may also stop by the lab and we will provide you with a pre-sterilized bottle to collect your sample in.
  2. Boil the jar and lid for 10 (ten) minutes or run them through the dishwasher.
  3. Select an appropriate sampling point.  The faucet you select should not have a swivel or a mixing control (i.e. it should have one knob for cold water and a separate knob for hot water).  Remove the strainer at the end of the faucet if there is one.  Good sampling points are frequently in the bathroom sink or tub.  An outside faucet is also fine if it is clear of contamination by dirt.  The kitchen faucet is usually considered a poor sampling point.  Do not sample through a hose or a frost-free hydrant.
  4. Let the cold water run for 5 (five) minutes before collecting the sample.
  5. Let the water run into the sterilized container without touching the faucet to the container. Immediately put the lid onto the container.
  6. Keep the sample cold (refrigerate or use a cooler) and bring it to the laboratory the same day it is drawn.  Analysis must begin at the lab within 24 (twenty-four) hours after sample collection for the test to be valid.

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Proper collection of a water sample for lead and copper analysis

  1. Drinking water that is to be analyzed for lead and copper should be collected using the “first-draw” technique described in #2 below.
  2. Water should be used the day prior to collection, but then be allowed to sit in the plumbing lines for six to eighteen hours.  Collection is performed on the FIRST water drawn from the cold water tap after the six to eighteen hour period has passed.  For most people, collection is most easily accomplished first thing in the morning prior to ANY use of water.  This includes the flushing of toilets, etc.
  3. Size of sample-one liter or a quart container.  The container need not be sterilized.
  4. Samples do not need to be refrigerated.  The sample must arrive at the lab within 14 days of collection.

Proper collection of water for nitrates analysis

  1. Fill a clean glass or plastic container with cold water.  The container should hold at least a pint, and it need not be sterilized.
  2. Refrigerate the sample until it is transported to the laboratory.
  3. Analysis of the sample must begin at the laboratory within 48 hours of collection.

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