by Don Prestly
From the September - October, 1999, issue of HANDY magazine.
Copyright © 2006 Handyman Club of America
Eliminating the "rotten egg" smell from your well water
Does your well smell? Does your sink stink? Is your tank rank? Do you blame your dog for that "rotten egg" smell? If you answered "yes" to any of these questions, we have the information and solution to help you zero in on the source and cause of your smelly water. And since there are more than 15 million wells in the U.S., you're not alone.
Hydrogen sulfide gas (H2S) is what gives water that rotten egg smell. H2S can occur in wells almost anywhere in the country, but it is especially prevalent in regions with coal deposits, such as Pennsylvania and West Virginia. It is also common in valleys and near rivers. In most cases, the odor doesn't mean that the water is unsafe to use, only unpleasant.
Zeroing in on the source of the smell is the key to correcting the problem. Is it only the hot water? Or is it both hot and cold? Here's what to do for either situation.
Going to the well
If the odor comes from both the hot and cold taps but diminishes as the water runs, the problem is most likely sulfur bacteria in the well and plumbing system. To correct this problem, you need to disinfect or shock chlorinate your well with a strong chlorine bleach and water solution.
The first step is to bypass your water softener and any water filtering equipment. The chlorine solution can ruin the softener's resin bed and the filters in the filtering equipment. According to Mike Convery, hydrologist supervisor for the Minnesota Dept. of Health, Well Management Section, you should not have to worry about the softener being contaminated. The brine solution is a very harsh environment where sulfur bacteria would not survive.
Next, turn off the power to the well pump. You need to pull the pump wiring out of the well casing so you don't pour the solution onto the connections.
Remove the well cap that seals the well casing. Brush away any debris, such as leaves or grass, or anything else that could accidentally drop into the well before removing the cap. Well caps are usually secured with machine bolts. You will need a wrench to loosen them.
Place the well cap in an empty bucket, not on the ground. Bacteria can contaminate the cap if it's placed on the ground and be introduced into the well when the cap is reinstalled.
Pull the pump wiring out of the well casing. Don't strain the wires when pulling them out or you could loosen the connections. If a wire does come loose, reconnect it immediately.
The bleach and water solution for shock chlorination is 2 gallons of unscented, nondetergent liquid laundry bleach, such as Clorox or Hylex, to 10 gallons of water. Don't use swimming pool chlorine. It's too strong. Pour the solution into the well casing. This is the only point at which the chlorine solution can be introduced and disinfect the entire system. Be careful not to spill the chlorine onto grass and other vegetation. Once you have poured the solution in, turn the power to the pump back on but don't push the wires back into the well casing.
To circulate the chlorine throughout the entire system, connect a garden hose to an outside faucet and stick the hose into the well casing about 3 or 4 ft. Run the water for 15 minutes. Running the water from the house causes the water pressure to drop in your system's holding tank, which signals the submersible pump at the bottom of your well to pump more water. The water that enters the pump mixes with the chlorine solution that's at the bottom of the well casing, near the pump.
Shut off the sillcock and remove the hose from the well casing. Reinstall the well cap. Then open each tap - this includes showers, toilets and tubs, hot and cold - and run the water until you smell chlorine. When you smell it, shut off the fixture. It's critical that the chlorine solution gets to the end of every water line.
The chlorinated water needs to sit in the lines for 8 to 24 hours so that it has enough time to kill the bacteria. However, don't leave the chlorine solution in the pipes for longer than 36 hours or you could be in for major problems. Jeff Dougherty, a certified water quality specialist with Aquarius Water Conditioning, told me about the owner of a $1.5 million home who left the chlorinated water in his lines for four days. The corrosion it caused created a couple dozen leaks and a costly mess.
After allowing the solution to work, you must flush the system before you drink the water. Attach a garden house to an outside faucet and let the water run until the chlorine smell disappears. This can take as long as two hours. Don't flush the system onto your lawn, gardens or directly into your septic system's drain field. It will kill the grass and could damage your septic system.
Once the smell is no longer present at the outside faucet, open each indoor tap and run it until the chlorine smell is gone. This small amount of chlorine won't harm your septic system.
In hot water
If only the hot water stinks, the problem is in the water heater. A water heater provides perfect conditions for creating hydrogen sulfide gas and can do it in a couple of ways. First, the warm environment is ideal for sulfur bacteria. Second, a chemical reaction between sulfate in the water and the water heater's magnesium anode rod can create hydrogen sulfide gas. Magnesium anode rods are standard in most water heaters and sulfate is a naturally occurring compound found in most groundwater. The magnesium supplies electrons that aid in the conversion of sulfate to hydrogen sulfide gas.
The first step is to replace the magnesium anode rod with one made of aluminum or an aluminum - zinc alloy. Aluminum and aluminum - zinc alloy rods don't contribute to the production of hydrogen gas.
Don't remove the offending rod without installing a new one. The anode rod is designed to corrode so the tank and fittings do not. You will void the water heater's warranty if you simply remove the rod. Replace - ment rods sell for around $20 at plumbing supply stores. You won't find them at home centers.
To remove the old rod, shut off the water supply to the water heater and drain about 5 gallons of water from the tank so that water doesn't run everywhere when you remove the anode rod. It's best to drain the water through the drain valve at the bottom of the water heater because you will also remove sediment that collects inside on the bottom of the tank. Sediment is another good breeding ground for bacteria. The water from the tank is very hot, so use caution.
Loosening the old anode rod nut can be difficult, since it probably has not been moved since it was installed at the factory. You'll need a 1 - , 1 - 1/8 - or 1 - 1/4 - in. socket wrench, depending on the nut size. It may take some real force to break the nut loose, so I recommend having a helper hold the water heater to keep it from moving. If the nut won't budge, apply some penetrating oil to the threads and try it again. If that fails, heat the nut with a propane touch. Use caution so you don't damage the top of the water heater. Once the nut is loose (and cool if you heated it), unscrew it and lift out the anode rod.
When you install the new rod, wrap some Teflon tape around the threads to make it easier to remove next time. Anode rods last anywhere from two to five years, depending on your water hardness. Check the rod every couple of years and replace it when the center core wire shows.
The old anode rod will most likely have a white, gray, black or reddish - brown slime on it that is produced by the bacteria. Don't attempt to clean the rod and reuse it.
You also need to treat the inside of the tank. The most effective way to fight the anaerobic bacteria is to oxygenate the water with hydrogen peroxide. Anaerobic bacteria thrive where there is little or no oxygen. The hydrogen peroxide bubbles and charges the system, creating a harsh oxygenated environment.
Pour in one pint of hydrogen peroxide per 40 gallons of tank capacity. This weak concentration is not harmful to you, but it will kill the bacteria. Install the new anode rod, turn on the water supply and refill the tank. Run all the hot water taps until they are hot and then turn them off. It's important to get the oxygenated hot water to the end of every hot water line.
Let the treated water stand for two to four hours. Then run each hot water tap for about five minutes to flush the peroxide. This also drains enough hot water from the water heater to clear the system.
Finally, whether you're shocking a well or oxygenating a water heater, don't expect it to be a one - time cure. A well may need to be shocked two or even three times a year. A water heater may need to be oxygenated three or four times in one year. It is unlikely that you will kill all of the bacteria in one treatment.
- Aquarius Water Conditioning, Oakdale, MN, (651) 473 - 5727
- Better Water Industries, Tyler, MN (507) 247 - 5929