Try this: fill a clear drinking glass with tap water, and hold it up against a white sheet of paper. What color do you see? Water can sometimes have a tint to it. Water can look yellow, pink, white (cloudy), or blue.
Water discoloration is likely a result of natural minerals and tannins leaching in from your plumbing or your water supply. How much of this material is in your water – and whether or not colored water is a sign of a problem – can vary. Consider these tips for evaluating your water and getting it tested.
Yellow Tap Water
If you wash a load of whites – and it comes out looking yellow – there’s a good chance yellow water is to blame. Yellow water often means you have small amounts of rust and/or tannins in your system. While rusty, yellow water might not sound ideal -- it's actually quite common.
How does it get there? All water has some level of iron in it: the iron concentration in wells and aquifers is typically between 0.5 and 10 milligrams per liter; in city water supply systems, it’s often less than 0.3 milligrams per liter. In both cases, this amount is too small to see, and won't result in yellow water. However, when that iron meets oxygen for a prolonged period of time, it can result in rust. If your water has a yellow color to it, it’s likely that your pipes have experienced some type of oxidation. This can happen in old residential or municipal pipes. While low levels of rust are considered safe – it’s a good idea to contract your water utility or have your home’s pipes and water heater inspected by a professional plumber. You can also flush pipes for a while to see if the yellow water goes away.
Pink water most commonly occurs from potassium permanganate, a chemical municipal water systems and homeowners use to oxidize iron when treating drinking water. In fact, after chlorine, potassium permanganate is the second most used chemical for fighting iron bacteria in drinking water.
While you may not have heard of potassium permanganate before, potassium – a naturally occurring alkaline metal – is found naturally in the earth’s water. Treated city water typically has a concentration of permanganate around 0.1 to 0.2 milligrams per liter.
Although considered safe, pink water can be a sign of an issue – typically with the municipal system. Flushing tap water can alleviate most pink water. If you notice an on-going problem, or testing indicates higher-than-standard-levels of iron bacteria, it’s a good idea to contact your water supplier.
Why is my water milky or cloudy?
Water that looks milky, cloudy or white is typically the result of tiny air bubbles in your water, much like the air bubbles in a carbonated beverage. These tiny air bubbles happen occasionally, typically the result of air particles in your pipes caused by colder weather. Cold water tends to hold more air than warm water, creating extra bubbles. A surge on your local water system can also create bubbles – a well being drilled at a nearby property, fire hydrants getting flushed, etc. These can affect your water pressure, leading to more bubbles – and cloudy water – than usual.
Cloudy, white water as a result of air bubbles is usually safe to drink, and the milky appearance should go away in a day or two. If it doesn’t, there may be a deeper problem you’ll want to investigate. For example, is air getting into your pipes? If so, you could have a small hole or rupture somewhere in your home’s plumbing. A repair may be needed.
Why is my water green or blue?
Unless you’re looking out at the ocean, blue water isn’t necessarily a welcome sight. In fact, blue or green tap water can be a sign that your water system is experiencing copper corrosion.
Copper corrosion in your pipes is no different than the iodized copper that makes up the Statue of Liberty. Years of rain and pollution caused the monument’s copper to corrode, giving it its familiar blue/green hue. If your pipes are copper, they can become corroded due to acidic sediment in your water or salt in your water.
While other water-color issues may be safe to consume – blue or green water is not. Be sure to have your water tested by a laboratory and your pipes checked by a professional plumber.