Friday, August 26, 2011

Brownish or Dirty Well Water after a Storm

With Hurricane Irene approaching the east coast and potentially heading for Virginia , it seems a good time to discuss how intense rainfall associated with hurricanes can impact your drinking water well, and what you should do if your well and septic system are impacted. Brownish or Dirty water coming from the well is a common occurrence after heavy rains when surface infiltration of water can carry dirt and contaminants into a well. If your well was flooded or your water appears dirty or brownish you need to clear your well and disinfect it. (Keep reading, I will tell you how to do it.)

An impaired pump, casing systems and improper well cap can allow surface water to flow down to the groundwater. Severe flooding can undermine a pump and casing system. A properly functioning well with a sanitary well cap should not be impacted by rain even a lot of rain; however if the entire well assembly is underwater it is unlikely that even a properly constructed system could avoid some infiltration contamination. The pump system consists of the well cap, well casing, and grouting. Surface flooding or excessive rain or could flow down the casing area if the grouting is damaged or the well cap not sealed properly. Often the grouting for the casing pipe which seals the well from the surface environment was improperly installed, has become damaged over time, or in the instance of some older wells were never grouted in the first place. This of course would also allow bacteria from the surface to enter the well during heavy rainfall. Sanitary well caps and grout seal are primarily installed to prevent surface contamination, especially bacterial contamination. Bacterial contamination of groundwater wells can occur from both above and below the surface. Pollution of entire groundwater aquifers affecting many wells may occur from failing septic systems.

Most wells impacted by storms and flooding do not remain underwater, but never try to operate a submerged well. Well pumps operate on electricity, you must wait until flood water have receded and dried out to try to operate the pump. Submerged pumps can generally be tried after the flood waters have receded. Wells in pits should have the connectors carefully inspected and all components dry before operation. If the pump does not turn on call a well contractor. The pumps and the electrical systems can be damaged by sediment carried with the flood waters. It is recommended that you hire a well driller or pump contractor to clean and lubricate the pump and restore power.

Extensive flooding can allow contamination to groundwater from many wells that were not properly sealed or whose well cap and grouting were damaged by the velocity of the flood waters. The EPA states that in areas of extensive flooding any well that draws from fifty feet or less (my well for example draws from around 50 feet below grade) or that is older than 10 years is likely to be contaminated, even if they seem fine. So if you have an older well, or draw from a shallow depth, or your water appeared dirty or brown, decontaminating your well. The instructions below are standard procedure from various state department of health and the US EPA

Run your hoses (away from your septic system and down slope from your well) to clear the well. Run it for an hour or so and see if it runs clear. If not let it rest for 8-12 hours and run the hoses again. Several cycles should clear the well. What we are doing is pumping out any infiltration in the well area and letting the groundwater carry any contamination away from your well. In all likelihood the well will clear of obvious discoloration. Then disinfect your well. This is an emergency procedure that will kill any bacteria for 7 to 10 days. After 7 to 10 days you need to test your well for bacteria to make sure that it is safe.

Determine what type of well you have and how to pour the bleach into the well. Some wells have a sanitary seal which must be unbolted. Some well caps have an air vent or a plug that can be removed. On bored or dug well, the entire cover can simply be lifted off to provide a space for pouring the bleach into the well. Take one gallon of bleach of non-scented household liquid bleach and carefully pour the bleach down into the well casing using a funnel if necessary. Wear rubber gloves, old clothes and protective glasses to protect you from the inevitable splashes. After the bleach has been added, run water from an outside hose into the well casing until you smell chlorine coming from the hose. Then turn off the outside hose. Now go into the house and one bathroom and sink at a time, turn on all cold water faucets, until the chlorine odor is detected in each faucet, then shut it off and move on to the next sink, or bathroom (if you have an automatic ice maker and water in your refrigerator dump the ice and run the water on the refrigerator also. If you have a water treatment system, switch it to bypass before turning on the indoor faucets. Once the inside system has been done, go back to the outside spigots and run the hoses until you smell chlorine coming out.

Wait 8 to 24 hours before turning the faucets back on. It is important not to drink, cook, bathe or wash with this water during the time period it contains high amounts of chlorine whose by products are a carcinogen. After at least 8 hours, run the water into a safe area where it will not kill your lawn, your trees or plants pollute lakes, streams or septic tanks. Run the water until there is no longer a chlorine odor. Turn the water off. The system should now be disinfected, and you can now use the water for 7 to 10 days when the effects of the disinfections wear off at that time test your well to make sure it is still safe to use.


  1. Hi there, very informative blog!
    I recently had my drains and septic tank cleared. The drain-guy attached his pressure washer to an outside tap that was directly connected to the well pump feed. The tap water is now brown and discoloured but does not smell. Could backpressure from his washer have dislodged corroded material in the pump? There is no well cap as far as I can see..just two pipes coming from the ground connecting to the pump and a pressure tank. I opened the pump itself and added 1litre of milton then circulated and bled to the taps until I could smell it. I had ran the taps for about half an hour but the water still had a brown tinge. From reading your blog I think I'll attach the hose to the outside tap that he used and run it for a longer time down the bottom of the garden away from any drains then disinfect again...Have you heard of this happening before after drains being cleared?


    1. Hi Brian, It sounds as if you might have overdrawn your well and run it down to the mud. Let it rest and it should recharge (if that is the problem). A liter of Milton to disinfect the well is a good idea. Though without knowing the depth and diameter of your well I cannot calculate for you how much bleach you need to reach 200 ppm. Email me at and we can continue the conversation.

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