In most cases, water takes on color as the result of organic matter from decaying vegetation.
Color is commonly a problem of only surface water; it is rare in water from deep wells or springs.
Color is also a result of the presence of metals like iron and manganese.
Common colors and what they indicate
Yellow. Often referred to as "tannins," indicates that humic acids are present.
Reddish water indicates precipitated iron. (The red color may be found on bathroom fixtures and laundry.)
Reddish brown is also an indication of iron which will precipitate when the water is exposed to air.
Blue indicates the presence of excess copper.
Dark brown or black indicates the presence of manganese and sometimes hydrogen sulfide.
Brown, Red, Orange or Yellow Water
Brown, red, orange, or yellow water is usually caused by rust. The different colors can be attributed to varying chemical oxidation states of the iron (rust) and by varying concentrations of the rust in the water. There are two major sources that can cause water to be rusty:
- The water mains, or
- The water pipes in your building.
Rusty water occurs from sediment in the pipes or rust from the inside walls of the water mains.The rust can be disturbed and temporarily suspended in water with unusual water flows from water main breaks or maintenance or by flushing of a hydrant. This discolored water is not a health threat. When the water is discolored it is recommended to either not wash laundry or to use a rust stain remover or regular detergent but not chlorine bleach as it will react with the iron to form a permanent stain.
The other major cause of brown, red, orange or yellow water is rusty water pipes in your building. If old, rusty pipes are discoloring your water, consult a licensed of plumbing materials or an experienced plumber. Water that is being discolored by rusty pipes is not a health hazard; however, it is an indication that the pipes are corroding and they can eventually leak.
The first step in solving a brown or yellow water problem is to distinguish if the problem is located in your building or if it is in your city or town water supply. The following are some common characteristics of a water main disturbance:
- The water was clear earlier but suddenly became discolored.
- Only the cold water is discolored.
- The water is discolored at all of the water faucets in your home and does not clear or improve after the water has been run for several minutes.
Some common characteristics of a corrosion problem in your building include:
- The water is discolored every morning or when first used after several hours of disuse.
- The water clears after it has run for a few minutes.
- The discoloration is only at one or several faucets, but not all of them.
- The discoloration is only in the hot water.
Iron can also occur naturally in a well supplying a public water system. The presence of iron can be confirmed through analysis of the water.
Another possible cause of brown (or black) water is manganese, the presence of which can also be confirmed through analysis.
Milky White or Cloudy Water
Milky white water, also commonly described as cloudy, hazy, soapy, or foamy, is almost always caused by air in the water. To see if the white color in the water is due to air, fill a clear glass with water and set it on the counter. Observe the glass of water for 2 or 3 minutes. If the white color is due to air, the water will begin to clear at the bottom of the glass first and then gradually will clear all the way to the top. This is a natural phenomenon and is caused by dissolved air in the water that is released when the faucet is opened. When you relieve the pressure by opening the faucet and filling your glass with water, the air is now free to escape from the water, giving it a milky appearance for a few minutes. If your water is cloudy or milky white in appearance and it does not clear in a glass after 5 minutes, if you are on public water system please contact the public water department in your city or town, or the MassDEP Drinking Water Program at your nearest regional MassDEP office. If the water is from your own well, please contact your local board of health. If you are outside of Massachusetts, contact the drinking water program in your state.
In cooler climates, the most common cause of green water is copper plumbing corrosion. If this is happening, the water will usually have a bluish-green tint and/or will leave a bluish-green stain on porcelain if the water drips from a faucet. Copper corrosion can also be caused by your electrical system being grounded to your water pipes, especially if you have a mixture of pipe material (e.g., some copper and some galvanized steel.). Green water may also be present in homes with copper plumbing that is less than two years old. The presence of copper can be confirmed through analysis. The EPA has a copper fact sheet.
Green water can also be caused by dezincification of poor-quality bronze alloys found in valves, water pumps, and water pump parts. This problem can occur in high-rise buildings and large industrial properties where the water is pumped to storage tanks. The water may also be tested for zinc.
During warm weather, green water may be caused by green algae in water supplies served by reservoirs or rivers. Algae are single-celled plants that readily grow in bodies of fresh water. Algae are not a health threat and reservoirs can be managed and monitored to prevent algae from growing to the point were they discolor the water. The water supplier through filtration may also remove algae.
Treatment of color varies. Activated carbon is the most commonly used color reducer. Anion exchange (usually following a water softener) is a common treatment for tannins, and certain types of macropore carbon are also effective at tannin removal. Iron and manganese coloration are treated in the standard ways that iron and manganese are treated. See sections on iron, manganese and copper for methods of reducing these contaminants and consequently the color alterations that they cause.