What’s that smell? Is it coming from your drains? Does your water smell funky when you pour it in a glass?
While stinky drains and smelly water are not fun to experience, they are fairly easy to fix. When you are aware of what causes these problems, you’ll be better able to prevent them from happening again too.
Water Heater Issues
If you detect a rotten egg smell in your water, it’s probably because of your water heater. The water heater is the perfect environment for bacteria growth because it is warm and moist, which will make your water smell “off.”
The other thing that is going on is your anode rod in the water heater may be faulty. It’s the piece that prevents corrosion in your tank. If you replace that, the smell should stop.
P-Trap
Check out the P-trap (which is the curved part attached to the pipe under the sink).
The P-trap holds smelly sewer gases at bay by placing a barrier between your home and the gases with 
water.
There are situations where that trap can dry out, which means that gas can permeate through your drains.
Try running the water in sinks and showers that have been idle for a long time.
Double check that the seal around the P-trap is intact. If it is leaky, it will run dry as well, so it is important to get it fixed.
Sewer Line Situation
If there is a musty odor coming from your drains, it is highly likely that it is because of a damaged sewer line. Because your wastewater isn’t flowing properly away from your home, a smell lingers.
Other signs of a sewer line problem are low water pressure, damp spots, sagging spots on your lawn and sudden unexplained hikes in your water bills.
You’ll want to get this looked after right away, because if you have a damaged sewer line, you are at risk for flooding should it rupture.
Blockage Preventing Ventilation
If there is something blocking your pipes (like food, debris, plant or tree matter or bird’s nests), the decomposition can produce an unwanted smell.
Similarly, this blockage will prevent the free flow of air through your pipes. Smelly gases get trapped and end up right back in your home.
Consider a regular drain cleaning or even a hydrojetting to make sure that your drains are running free and clear- and odor-free.