Our first reaction to bad smelling water is usually “my water is contaminated.” However, our water’s smell can have other implications and causes:

  • Increased use of disinfectant (e.g., chlorine)
  • Seasonal water quality effects (e.g., snowmelt or bacteria growth)
  • A change in where your water comes from or how it is treated (e.g., a change in water supply)
  • Moving from one area to another (e.g., buying or renting a new home)
  • The age and infrastructure of your plumbing

Take a sudden change in your water’s odor seriously. If the smell of your water becomes unbearable, or if this is the first time you notice the smell, you should contact your water supplier immediately.

Ask your neighbors if they are experiencing odor problems - this will allow you to see if the problem is with your home plumbing or the local water system.


Rotten Eggs, Musty, Earthy, Grassy

Hydrogen sulfide, sulfate-reducing bacteria, softwater reactions in electric water heaters, algal by-products, bacteria, surfactants

Rotten Eggs, Musty, Earthy, Grassy



Gasoline or oil contamination and possibly nuisance bacteria

Gassy or Oily smell


Methane-like Gas Smell

Organic decomposition and natural gas leak (sulfur-additive)


Sweet, Plastic, or Tarry

Industrial or gasoline contamination



Organic chemicals or industrial contamination