How to Disinfect Your Home Well and Water System

If your well or water system in your house has been contaminated in some way by surface water, sewage, back-siphonage; or your system has had a test positive for coliforms, you can disinfect your well and pipes in your home yourself.

1. Check your system to find the source of the contamination:
   - Check the pipes around the pump and well head for leaks.
   - If pooled surface water entered your well, you may have to raise the well casing, or pour a concrete slab around it to protect it. You may need to add earth fill, or grade the area around the well so water does not collect there. If you find that your well is in a flood plain, consider drilling a new well.
   - Check the piping in your basement or crawl space for leaks-both in the culinary (drinking) water and waste water.
   - Look for pooling water, drips, or other defects. Look for odd connections, or poorly-done repairs that could let sewage enter the culinary water.
   - Check your garden hose and spigots. Hoses left in puddles or containers of water can admit dirty water if your system loses pressure. This can occur during a power outage, when there is no pressure on the system from the pump. When pressure in the house system falls, dirty water can be siphoned back into the pipes or well. A device to prevent Back-flow is available at any hardware store and just thread on the spigot.
2. Open all the taps inside and out and flush the system 20 to 30 minutes. Remove aerators and shower heads, since they catch and hold any sand that may be in the pipes. This will also clear any sediment out of the pipes.
3. To disinfect, get one gallon of plain laundry bleach, such as Chlorox, Purex, or a store brand, containing 3% to 5% sodium hypochlorite. Use plain bleach with no dyes, detergents or perfumes! Read the label carefully. Pour one gallon down the well casing into the water. Allow to sit in the well overnight, 8-12 hours.
4. Flush this water through all the taps and spigots in the house until the chlorine smell is gone. Remove aerators and showerheads (if you have re-installed them), and you may want to open some windows. You may also want to flush water heaters, pressure tanks, spigots serving the washing machine, and other lines. This will also disinfect these lines.

Do no drink heavily chlorinated water, or use it for cooking, laundry or bathing! It has too much chlorine! Wait until the chlorine smell disappears!

Don't put heavily chlorinated water into your sprinkler system or water animals with it!

Your well and household systems should now be disinfected. You should put your aerators and the rest of the system back together. Your can also bring in another water sample for analysis to prove disinfection. This may be required if you are working with a bank or mortgage company on a sale or refinance.