Environmental Laboratory Service

Coliforms in your Well

If the laboratory finds coliforms in your well, you should disinfect your well water system. There are two sources of the most common well disinfectant, chlorine: household bleach and calcium hypochlorite. Household bleach is 5% chlorine and is easy to use. We recommend the following procedure:

1. Pour one-half gallon of household bleach down the well.
2. Cap the well and go back to the house.
3. Turn on the kitchen and bathroom taps and run water until you detect the chlorine smell. This may take about five minutes.
4. Turn off the taps.
5. Go back to the well and pour the remaining half-gallon down the well.
6. Do not use the water for 24 hours.
7. After this period, flush the lines by washing a load of whites, or running the bath or dishwasher.
8. Retest for coliforms in four to seven days of normal water use.

If you have evidence of a high iron concentration in your well, such as stains on structures that come in contact with water, or orange, rusty stains on bathroom fixtures, do not use chlorine because chlorine will aggravate the iron problem.

A stronger source of chlorine is calcium hypochlorine. It comes in a powder or tablet form and is 68 to 70 percent chlorine. An equivalent of two tablespoons of calcium hypochlorite (powder or tablet) can be put down the well in the same manner as the bleach. Be sure to turn on the water in the house so that you bring chlorinated water into the pressure tank and through the lines of your home. Wait seven to ten days of normal water use to retest the well for coliform.

The well may require more than one application of chlorine. Once you have cleared the well and pressure tank of heavy bacterial growth, it is advisable to routinely add a cup of household bleach to the well at least once a month. This will prevent a build up of bacteria in the pressure tank. If your well has a recurring bacteria problem, you can install a chemical feeder pump that will add a continuous dose of chlorine solution to the water as it is pumped from the ground. Generally, the solution is made up of one part chlorine and four parts water. The feeder can be adjusted to maintain a chlorine residual at the kitchen tap. Use a chlorine test kit designed for swimming pools to determine the chlorine residual at the tap. Adjust the feeder so that you measure 0.5 parts per million (ppm) chlorine residual at the kitchen tap.

A new method for killing bacteria found in well water is ultraviolet (UV) disinfection. Water pumped from the well travels through a pipe that is surrounded by lamps emitting ultraviolet waves. The UV wavelength will kill bacteria in the water before it travels into your home. It requires no addition of chemicals. The UV system tends to be easily fouled by waters containing high concentration of iron, calcium or manganese. These wells will force a more rigorous maintenance of the lamps to remove precipitation of these compounds. Consult a water treatment system company for cost and application of an UV system.

Tips for Preparing Sample Coolers for Transport/Shipment

Proper packaging and cooling of samples is a means to help prevent re-sampling. These tips will help protect sample containers from any impact they might receive when being shipped and ensure that the sample temperature is within the 0-6°C temperature range.

1. Use a transport device that conforms to DOT drop test specifications. A typical ice chest/cooler utilized by Guadalupe-Blanco River Authority conforms to these requirements.
2. Keep the samples on ice. Regular “wet” ice is the best choice for keeping samples cold. Double Bag the ice to prevent water from leaking from the cooler. Large durable plastic or garbage bags work very well in containing melted ice. Blue ice packs are generally not sufficient to adequately maintain the temperatures for sample coolers.
3. If a sample is above temperature when collected, pre-chill the sample in iced water for a few minutes or place in the refrigerator for a longer period of time before packing the cooler. This aids in lowering the temperature of the sample quicker and prevents the ice from having to both lower the temperature of the sample and maintain it.
4. At least 1/3 of the cooler space should be allowed for ice. Use 20-25 pounds of ice for an average sized 50-quart cooler. When in doubt – USE MORE ICE. Ice and the associated cost of shipping a heavier cooler is typically much less than having to potentially re-mobilize a crew to re-sample.
5. Isolate each sample container with packing material such as a bubble bag. Glass containers especially tend to break easier during shipment when they are in direct contact with one another. Do not stack glass containers in the cooler or lay glass on its side-they could break. Use a larger cooler or multiple coolers if necessary.
6. Seal each container in bubble bags or Ziploc baggies to prevent water from seeping onto the sample, the label or Chain of Custody when the ice melts. Taping the end of the bag with duct tape also helps.
7. SEAL the entire cooler with DUCT tape…especially the lid. This will help prevent leaks. Some carriers are beginning to reject “wet” boxes or coolers due to the damage caused to other boxes and packages.
8. USE BUBBLE BAGS! Not only is it the ideal packing material for maximum shock protection, the trapped air provides thermal insulation and helps to keep the samples cold.
9. DO NOT USE packing material that absorbs water. Material such as paper, cardboard and Styrofoam peanuts become soggy and decompose in water thereby loosing their cushioning effects.
10. DO NOT USE vermiculite. It does not work well in coolers. It tends to scatter when dry and becomes a soggy mess as it clumps up when wet. Additionally it tends to prevent samples from rapidly cooling down.
11. Never use dry ice. Dry ice could potentially freeze samples compromising sample integrity and possibly shattering glass containers. Dry ice also poses a safety hazard and potential problems if shipping via a commercial courier such as FedEx or UPS.
12. Avoid using water-soluble ink. Blurred ink could be difficult to read and sample identification could be compromised. Call the Guadalupe-Blanco River Authority Lab (830-379-5822) if you should have any questions or packaging difficulties.

GBRA Lab Sample Acceptance Policy

GBRA Lab Sample Acceptance Policy indicates the minimum conditions a sample must meet on receipt at the laboratory. Sample collection personnel are to use water resistant ink, use appropriate sample containers, adhere to holding times, and sample volume requirements. Deviations from the Sample Acceptance Criteria will be documented on a GBRA Non-Conformance form and/or the Chain of Custody (CoC), as well as the final report.

The laboratory by checking samples for the following qualities for chemical and bacteriological samples, where appropriate, to evaluate sample acceptance:

Thermal preservation – The sample temperature must be between 0-6°C. Samples delivered to the lab the same day as they are collected are not likely to have reached a fully chilled temperature. Samples shall be considered acceptable, without qualification, if there is evidence the chilling process has begun. The temperature for each sample and the presence of ice will be recorded on the CoC.

pH check – The pH of samples requiring acid/base preservation is checked upon sample receipt and documented on the CoC, along with any preservation performed by the laboratory.

Chlorine check – All (Drinking water, non-potable and construction) bacteriological samples must be submitted to the laboratory in approved sample containers. Containers are available upon request. The client is responsible for recording the Chlorine Residual on the CoC. If Chlorine Residual is not indicated a qualifier will be added to the final report.

Sample integrity – All samples are checked for sample integrity with the following criteria:

1. Approved container based on the type of analysis requested.
2. Cracks, leaks, possible contamination and/or any factors that could affect the integrity of the sample.
3. Adequate sample volume and air space.
4. Hold times for requested analysis must not be exceeded.

Chain of Custody (CoC) – Information on the CoC must be properly and fully completed. Sample collectors are urged not to utilize photocopies of CoCs. We prefer that the customer fill out the necessary information by hand, when possible.

If the checks performed upon sample receipt indicate the criteria are not met, then:

1. The sample custodian will place a call or email the client for instruction.
2. The decision to proceed is documented on the non-conformance form and agreed upon with the client. In the event the client cannot be contacted immediately, the sample(s) is placed on “hold” status. We will not log in the sample until we are given instruction by the client and instructions are documented accordingly. If there is no response within 3 working days the sample is automatically rejected.
3. Subsequent client contact to address the sample conditions are also documented on a non-conformance form or CoC and the sample is processed accordingly. (emails/phone calls or faxes)
4. A Q (Qualifier) will appear on the final report with a brief explanation if the sample criteria have not been met.