How to flush

Update (1/26/14):Excellent article on how and why to flush your plumbing system by environmental engineering professor Andrew Whelton available here.

Governor Tomblin and WV American Water have instructed households in the “safe” zones to immediately flush their household water systems to attempt to remove MCHM from pipes and hot water tanks. Although we are neither chemical experts nor plumbers, this page includes recommendations from folks who have been involved in water testing in Charleston and also those who have experience with rural septic systems. We make no claim that following these recommendations will remove all MCHM and other contaminants from your pipes. As this video with WJU Professor Ben Stout makes clear, MCHM may be difficult to remove from water tanks because it is not very soluble in water.

If your home is on a sewer system ( no septic tank):

West Virginia American Water issued these guidelines for flushing, which instruct people to flush 15 minutes of hot water and 5 minutes of cold water through each tap (including outdoor taps) and explains how to flush appliances. Federal officials recommend a lengthier flush, flushing until the chemical smell is gone. The smell is apparently noticeable at levels below 1 ppm.

This video (starting at about 4 min) from a university engineering professor explains the importance of flushing your pipes and provides additional recommendations, which are also discussed in this set of answers to common questions about flushing.

Flushing your pipes as soon as possible will minimize absorption of the chemical into your pipes, degradation of your pipes, and contamination of your neighbors who have already flushed.

Keep your house well ventilated during the flushing process. Open all windows and doors and turn on fans. As an additional precaution, people who are not helping with flushing should leave during and for several hours after the flushing process.

Turn off the electricity to your electric hot water heater or the gas to your gas water heater before beginning the flushing process. Drain the hot water heater from the bottom, by connecting a house to the drain valve located at the bottom of the heater. If your water heater is very clogged with sediment, this make take awhile.

Larger homes have a greater volume of water in their pipes and should probably flush longer.


If your home is on a septic system:

Flushing is still important, for the reasons discussed above. However, the Kanawha-Charleston Health Department recognized that pumping hundreds of gallons of water through septic tanks could seriously damage or shorten the lives of septic system leach fields.

A septic system essentially consists of a tank ranging from 500 to 2500 gallons capacity and piping leading out of that tank to a leach field which allows for the excess water to be drained from the tank where it leaches into surrounding soil. Most leach fields depend on gravel or a series of baffles below the surface of the soil. The leach fields must be porous so they can quickly absorb large amounts of water before that water soaks into the soil.

Septic tanks depend on maintaining three separate layers on the interior of the tank. Solids that are heavier than water sink to the bottom. Liquids that are lighter than water, fats, soaps, etc., rise to the top. The water inlet, from your house, and the water outlet, to the leach field, are both at the middle of the tank. The leach field outlet is located so that only water will leave the tank under almost all conditions. Every few years, the tank should be drained by a local sewage hauler to prevent solids in the tank from building up and being drained out to the leach field. The life of the leach field and the effectiveness of the system depend on solids remaining in the tank. If solids are drawn out of the tank, they will clog the leach field and water will no longer flow freely from the tank. The tank will back up and water will begin leaking into the soil from the tank’s lid. The homeowner will either have to construct an entirely new leach field or an entirely new septic system. (See here for more on septic systems.)

Septic tanks are typically sized to handle about 150 gallons of water per bedroom per day. If septic system owners follow the flushing instructions that have been advertised by Gov. Tomblin and WV American Water, they will simply turn on their water taps and let the water run into their drains. In rural areas not served by public or private sewer systems, this means flushing hundreds of gallons of water directly into septic tanks in a relatively short period of time. Putting this much water into a septic tank will cause the water to swirl around in the tank, mixing solids from the bottom of the tank into water flowing into the leach field. As described above, these solids will flow into the leach field block the normal absorption of water into the soil. Large amounts of water flowing into the leach field will, by itself, cause the whole system to back up, forcing leaks back out of the septic tank and causing drains to back up in your house. Even if your system does not clog right away, solids in your leach field will take years off the overall life of your system. Possible flooding of the leach field or blockages due to solids in the septic system outflow were noted as potential problems by the Kanawha-Charleston Health Department.

WV Department of Health and Human Resources has published these guidelines for homes on septic systems. They recommend flushing smaller volumes of water to reduce how much goes into your septic system, and also suggest running hoses from taps to drain the water outside (buckets might be a more manageable option). Although DHHR doesn’t mention this, in our opinion, you could also do smaller flushes over a several day period.

We have also received this additional suggestion from a rural resident who plumbed his own house and has lived with a septic system for 35 years. To reduce the amount of water that you have to flush through your septic system, you may also want to consider draining your entire plumbing system out onto the ground, as far from your house as your hoses will reach, before flushing the system into your septic tank.

  • Turn off the water where it enters your house from WV American Water.
  • Attach a garden hose to your outdoor faucet and run the hose as far away from the house as possible. Open the faucet.
  • Open the faucets in your house that are at the highest points in your water system. This should bring air into your system and allow most of the water in the house plumbing to run out of your outdoor faucet.
  • Turn off the electricity to your electric hot water heater or the gas to your gas water heater. Attach a garden hose to the bottom drain of your tank and run the hose outside, as far from the house as possible. Open the valve on your hot water tank.
  • Open the hot water faucet that is at the highest point in your system so that all your hot water lines will drain back into your tank.
  • When the entire system and hot water tank are empty, close all the valves, including the drain valve on the hot water tank.
  • Open one faucet and then open the valve from WV American Water. Allow the entire system, including the hot water tank to fill with water. DO NOT turn on the electricity or gas flame to your hot water tank.
  • Turn on all your faucets to make sure that water lines to all faucets are full.
  • Turn off the valve from WV American Water again and begin the whole process step by step from the beginning. It probably makes sense to do this draining/refilling cycle multiple times

Because no one knows the safe level at which the 6 chemicals in Crude MCHM can be used, there is no guarantee that these recommendations will result in water that is safe to use. By flushing these chemicals into your septic system, you still risk damaging the septic system.