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Protecting your well

Posted: December 30, 2011

Wells can be protected from contamination by bacteria and chemicals through good management practices. A sealed well cap prevents insect entry along with any bacteria they are carrying. Hazardous materials can be kept out of the well's recharge area. Water testing verifies the success of these protective practices.
A sealed well cap to exclude bugs

A sealed well cap to exclude bugs

A couple married for 61 years brought me a water test report for clarification. They have tested their well periodically for years and for the first time they had a positive total coliform test. They had the usual questions, “is that bad? (we haven’t been sick or anything).” And, “what should we do about it?” This couple is to be commended for their regular habit of water testing. That they tested this fall was wise – all the wet weather may have been responsible for the high coliform count. You can read more about the mechanics. For some ideas about what to do about a positive test, read on.

Wells have a watershed – rain falling within the watershed percolates to the water table and supplies the well with water. The size of the area depends on the amount of water withdrawn from the well. A typical residential well collects enough water from rain falling inside a circle of 100 ft radius to supply the household. On sloping ground the area must be stretched in the uphill direction. Extending the "sides" of the circle to the crest of the hill defines the watershed area of the well and results in a "hot dog" shape. If you talk to a hydro-geologist about this, they will tell you that you can’t exactly define the watershed area for the well unless you monitor the water table around the well while it is in production. That is true, difficult, time consuming, and expensive. The simplistic approach above has the practical advantage of describing an area that you can define and protect from activities that can pollute your well. Why not fuel your lawn mower outside this area and protect your water from a fuel spill? Why not fertilize or spray other parts of your yard first - making sure the application rate is correct - then do the watershed area? Why not make sure the dog’s business is conducted outside the watershed area?

This couple also considered the possibility that insects were responsible for the high bacteria count. Earwigs and other insects can crawl under the typical well cap and fall down the well carrying coliform bacteria with them. The couple liked the sanitary well cap shown in the picture and plan to replace the current cap on their well. The cap has three pieces. A top cover, a bottom ring, and a rubber gasket sandwiched between the two. When the top cover and the bottom ring are bolted together the gasket is compressed completely sealing the top of the casing from the insect world.

They plan to shock chlorinate their well and do a follow up test to verify that bacteria were eliminated from their water supply. They also plan to discontinue the use of a carbon filter when they learned that such a filter can encourage bacteria growth.

When asked about the secret of 61 years of happy marriage, do you think they said “high quality drinking water?” No! The husband said “choose a good wife,” and his sweetheart smiled in agreement!

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