We always expect clean and safe water to be coming out of our water taps at home, so what can you do if your water starts to smell “dirty?” There could be many causes to a “dirty” water smell, depending on what it smells like, whether the smell is coming from the water itself or the plumbing or the water heater. A “dirty” smell in the water could smell like dirt, or maybe rotten eggs, and is most often caused by bacteria somewhere in your system, or the water source.

The Cause of the Smell

A smell around the sink area that only appears when you turn on the water may make you think that it is the water itself that smells, but it could be the drain. Bacteria in the drains built up from food, soap or other particles will create heavy gases as they metabolize the biological materials around them, which then will be forced out of the drain and into the open air anytime water is being flushed through the drains. To be able to determine whether it’s the pipes or the water that smells, fill up a glass with water, then carry it away from the sink before smelling it. If it smells clean, the issue is likely in the drains.

If you have a “dirty” smell coming from your water, it could also be the result of hydrogen sulfide in the water coming from the source. Hydrogen sulfide gas is toxic to people, but you will most likely smell it before it reaches any toxic levels. Hydrogen sulfide gas is detectable by humans when its concentration is as low as .5 PPM, anything less than 1PPM has a musty smell and 1-2PPM is a rotten egg smell.

There are cases when the “dirty” smell of the water only happens when you have your hot water on. In this case, your likely culprit is going to be your water heater. Bacteria can grow within a water heater if the temperature is set too low to kill the bacteria naturally, or if the water heater has been turned off for too long (which often happens when going on vacation). Bacteria built up in a water heater is not always not harmful to humans, but will need to be cleared out to rid you of the smell.

Solutions for Removing the Smell

Once you have determined whether the smell is coming from the water itself, or the pipes, you can decide what to do about the smell. If it’s coming from the sink or the drain attached to it, the best solution is to disinfect the area using a small amount of soap and a brush to clean all the surfaces you can reach.

In the case of the hot water being the issue, you can try turning up the temperature on your water heater for 24 hours and running your hot water taps in order to flush out your pipes. Make sure everyone in the household knows the temperature has been increase though, because it will likely be within a scalding range.

If your home is serviced by a well, or you haven’t been able to narrow down the cause of your “dirty” water smell, you should consider contacting a water testing lab, or ordering a water testing kit online such as those available from AquaKnow, to test the hydrogen sulfide levels in the water.