Turning on your tap and seeing discoloured water can be very unsettling. While discoloured tap water isn’t always dangerous, it’s still something you shouldn’t ignore.
The specific water colour can tell you a lot about what’s going on in your plumbing or water supply. This guide breaks down the most common causes of discoloured tap water, what each colour might mean, and how to fix the problem.
Table of Contents
Yellow, Orange or Rusty Water
This type of discoloured tap water is usually due to iron in the water, which can be either:
- Ferrous iron (clear water iron): Dissolved in the water, turns yellow or orange after sitting.
- Ferric iron (red water iron): Already oxidised, appears rusty or orange immediately.
However, the cause of the colour change may depend on whether you’re drinking from a public or private water supply.
- Often caused by maintenance work, repairs, pipe flushing, or nearby construction.
- These activities can loosen rust or sediment in the pipes, causing discolouration.
- Typically clears up on its own after a short time.
The colour change may be due to:
Iron
> Often accompanied by manganese.
> Manganese can cause black stains or slimy buildup.
> If the water has a metallic taste, iron is likely the cause.
Iron bacteria
> Natural organisms that combine iron/manganese with oxygen, creating yellowish slime or oily surface.
> These bacteria are not harmful to health but can clog pipes and cause unpleasant smells.
Tannins
> Organic materials from leaves, roots, or soil, especially in areas with peaty ground.
> Tannins can make water look dirty, taste bitter, and smell musty. Though not harmful, they can make the water unpleasant.
Brown or Murky Water
Brown or murky water usually results from sediments (tiny particles like sand, soil, or rust), making the water look muddy or cloudy.
While this doesn’t always mean the water is unsafe, it can allow bacteria to grow more easily. Again, the cause for this type of discoloured tap water may depend on your water supply:
- Public Water Supply: Changes in water pressure or a switch in water sources (e.g., from a lake to a river) can stir up naturally occurring sediment that usually settles in the pipes.
- Private Water Supply: A broken well screen, damaged pump, or increased runoff after storms can let extra dirt and grit into your water.
Solution: Install a sediment filter. If the issue persists, inspect your plumbing or well system. Water testing is also helpful to rule out harmful contamination.
Green or Blue Water
While rare, green-blue discoloured tap water is cause for more concern. It may indicate algae contamination or copper corrosion.
Algae:
- Can grow in private wells, especially during warm weather. If the water smells bad and looks greenish, algae is likely the cause.
- At high levels, cyanobacteria (toxic algae) can be harmful, so testing the water is important before drinking or cooking.
Copper Corrosion:
- Occurs in older plumbing systems with copper pipes, where the pipes break down and leach copper into the water.
- High levels of copper in water can pose health risks, especially to children.
Solution: Treat algae with shock chlorination. Copper corrosion can be addressed by adjusting your water’s pH or installing a reverse osmosis system.
Cloudy or White Water
The most likely cause for this type of water is harmless air bubbles. This occurs when water is under pressure in your pipes, and once the water is in a glass, the air escapes, causing cloudiness to disappear from the bottom up.
It is common during colder months when cold water can hold more air or after recent plumbing repairs or changes in pressure. If cloudy white discoloured tap water persists, it may be caused by:
- Suspended solids (tiny particles that don’t dissolve), which might come from soil runoff, construction, or disturbances near your water source.
- Hard water (calcium or magnesium) can cause cloudiness and leave a chalky film on fixtures.
- Methane gas can cause bubbling water in well systems. While odourless and flammable, methane should be tested immediately if suspected.
Oily or Rainbow-Coloured Water
If you have discoloured tap water that appears oily, it may be as a result of:
Iron bacteria: Form a slimy layer that clogs pipes and makes water look and smell unpleasant. They’re harmless but need to be managed.
Petroleum contamination: Rare but serious. If the water smells like fuel or oil, stop using it immediately and have it professionally tested.
Prevention:
- For iron bacteria, keep your well cap sealed, disinfect your system regularly, and avoid placing equipment on the ground during repairs.
- Petroleum contamination requires immediate testing and action.
When to Test Discoloured Tap Water
Whenever your tap water changes colour, smell, or taste, it’s a good idea to get it tested. A simple lab test can help you identify what’s in your water and determine the appropriate treatment. Guesswork can lead to wasted time, money, or even health risks.
Testing is especially important for private water supplies. Regular water testing (at least once a year) is recommended to ensure water safety for private well owners.
At Southern Scientific, we offer reliable, professional water testing to help you identify the cause of discoloured water and find the right solution. Whether dealing with sediment, iron, algae, or other issues, we can guide you toward the best course of action.
