Regardless if a water well is new or existing, water sampling must be done with special consideration to obtain a good water sample and avoid additional contamination. Please read this document completely, as it outlines the correct procedure for taking a water sample.
All samples must include a sample label on the container (or write the sample information directly on the bottle). All sample label must include the PWSID number, date and time of sample collection, sampler’s initials and the address/location where the sample was collected. Any sample submitted without a label will be rejected and a replacement sample will need to be submitted.
1. Obtain an approved sterile sampling container and current Water Sample Form. These may be picked up from our office or the City of Houston Water & Dairy Laboratory. Do not use jars or other containers from home or other sources. Use approved water sample containers only.
2. Select a cold water faucet or tap nearest the well. Most wells have a faucet located on the water line exiting the tank. Samples should come directly from the well or the tank.
3. Remove anything attached to the faucet. Hoses, aerators, or anything else attached to the sample faucet may cause contamination.
4. You want fresh well water in your sample. Turn on the tap or faucet. Let it run for at least ten minutes so that the well pump is activated and you obtain a fresh supply of water from the well.
5. Do not get your hands dirty. While the water source is running, wash your hands thoroughly with soap and water. Do not handle animals, place anything in your mouth, or do anything that might contaminate your hands and cause the water sample to become inadvertently contaminated.
6. Turn off the faucet and sanitize it. If the faucet is metal, it can be done by heating it with a cigarette lighter or a propane torch. Heat the faucet until it is dry. If the sample is to be taken from a plastic or chrome faucet such as your kitchen sink, do not heat it. Swab inside and around the opening of the faucet with a cotton ball soaked in rubbing alcohol or use a spray bottle containing a water/bleach mixture.
7. Collect the sample. Turn the faucet on to a slow trickle. Carefully open the water bottle making sure not to touch the inside of the cap or the bottle threads. Fill the bottle to the neck and secure the cap. While filling the bottle, do not lose or rinse out the white substance inside the bottle. This is sodium thiosulfate. Its purpose is to neutralize any chlorine in the water sample.
8. Protect the sample. Keep the sample out of direct sunlight and away from heat. Until you are ready to bring the sample in, keep the sample cool, not frozen, in a refrigerator or cooler. After you take the sample, you have twenty-eight (28) hours to deliver it to the lab.
9. Fill out a sample form. Complete the form using black ink only. Make sure the information is complete. If you have a Public Water System, make sure to include the ID number in the space provided on the form. If you have a chlorinated well, make sure to test the chlorine residual and include that information in the space provided on the form. After completion of the form, include a check or money order for $16.50 payable to the City of Houston. No cash. If you have an account with the Houston Lab, include your account number on the form or the sample may not be processed.
10. Get the sample to the lab. As a courtesy, this office will courier water samples submitted on Wednesdays between the hours of 8:00am and noon. You should receive the laboratory report within 7-10 days. The following information will be required to locate the results: (1) the date the sample was brought in (2) the county in which the sample was collected and (3) the return address exactly as the form was completed.
11. What the laboratory report means. If coliform organisms are not found, the water is bacteriologically safe to drink. If coliform organisms are found, the water contains bacteria commonly present in sewage which might include typhoid or other disease producing bacteria. Contaminated water should not be used for drinking or washing teeth, wounds, or vegetables which are to be eaten raw. Use bottled water until the water supply is decontaminated. Contaminated water may be boiled for a minimum of 20 minutes or may be treated with 6 to 10 drops of household chlorine bleach per gallon at least 30 minutes before use.
12. How to treat a contaminated well. Obtain 1 gallon of chlorine bleach. Dilute it with 5 gallons of water and pour it directly into the well casing. Connect a garden hose to a faucet near the well and let it flow into the well casing until the odor of bleach is detected from the hose. Shut off that faucet and open all other cold water faucets until the bleach odor is detected from each faucet. Then open all hot water faucets to allow the bleach into the cold water line serving the water heater. Let the bleach remain in the well and piping for at least 4 hours, preferably overnight. Then open one exterior faucet and let the water run until the bleach odor is gone. Next flush each cold water faucet similarly. Wait 3 days before taking a new sample to the laboratory. It is not unusual repeat this treatment 3 or 4 times before no contamination is found by laboratory tests. All wells should be tested for contamination at least twice each year.
Water samples are only tested for the presence of fecal coliform bacteria. If you desire your water tested for other substances, contact the Texas Commission of Environmental Quality at (713) 767-3500 for further information.
Contact the Environmental Health Department at 281-342-7469 for questions.