What are some causes of dirty water?
There are two main causes. The first possible cause is that there is an issue in the distribution system, such as:

  • Main Breaks: Water is delivered to your home or business through a network of underground pipes referred to as the distribution system. The principal pipe or conduit is called a main. Water mains in this distribution system can fail due to age, corrosion, high pressure surges, defective materials, or damage by construction work. Fire hydrants can also be broken off by vehicles. When a main breaks, the increased velocity of the water can pick up dirt and other materials that normally settle to the bottom of the pipes.

  • Dead Ends: every distribution system has mains that must be ended due to physical obstructions (rivers, roads, etc.) or city design features (sports complexes, cul-de-sacs,etc.). This results in a "dead end" that does not connect back with another main. Low usage in these areas results in sediment accumulation. Over time the lack of circulation can result in the appearance of discolored, foul tasting stale water.

  • Fires and Fire Hydrants: the high velocity of water used to fight fires and to test fire hydrants can pick up sediment as described under Main Breaks.

  • Construction Activities: sometimes mains must be replaced or cleaned. Also, new buildings require connection to the existing water main. These and other similar activities may disturb the accumulated sediment and result in temporarily dirty water.


Private plumbing systems can also cause dirty water. This can happen for a number of reasons:

  • Hot-Water Systems: dirty water often originates in the hot-water tank. Hot water tanks can accumulate sediment and therefore need to be flushed clean.

  • House Piping: defective plumbing can lead to many dirty water conditions. Pieces of rubber or plastic washers that age and crumble can result in particles in the water. Improperly joined dissimilar materials (such as iron and galvanized, or copper and iron) can accelerate corrosion and turn water red or green. Rapid shut-off of faucets or automatic valves in washing machines can cause tremendous pressure surges that dislodge material from pipe walls.

Show All Answers

1. Why is my water discolored?
2. What are some causes of dirty water?
3. What should I do if I have dirty water?
4. Does the Water Department give discounts?
5. Should I contact the Water Department if I feel my billing is wrong, regardless of whose favor it is in?
6. Some months my water bill seems very high. Why is that?
7. What if I don’t want City water?
8. Why does my water bill run the same amount month after month?
9. Why does my water bill sometimes vary from month to month?