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I just moved into my house with brand new PEX (uponor) plumbing. I used clear for the hot and cold instead of red and blue, because I bought everything myself and I thought it would prevent wasting too much. I installed the PEX tubing myself after buying a new Milwaukee tool. This was my first PEX DIY project, but I have a fair bit of experience with lots of remodeling trades.

Anyway, we have been using the plumbing for about 6 weeks. I just noticed that the hot water tubing right near the water heater (commonly abbreviated as HWH) now has a green hue for about 12-24" past the heater. The water itself is not stinky or green - although I do notice a slightly different smell than with my old copper plumbing. There is about 3 feet of SS flex and copper between the water heater and the PEX. Our County inspector approved everything. The water heater is electric and it is about 5 years old, purchased from someone on craigslist. The water heater was empty when I moved it into the house, but I didn't try to clean it with anything.

So, what is causing the PEX tubing to turn green? Should I make the water heater hotter? I don't think it is above 120F, but I haven't measured it. Should I figure out how to inject bleach into the system every once in a while?

Edit: added picture. It turned out better than I expected.

pipes coming from water heater are on the left

brfox
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8 Answers8

7

I am a professional plumber and I have been using PEX tubing for 20 years and I am also manufacturer-certified to do so.

The only time I've ever seen this green color in PEX tubing it was algae. The pipe was a cold water supply line that was wrapped with heat tape and pipe insulation, and run above ground underneath my camper. When I removed the pipe it had algae growth along its whole length.

However, the algae will not stick to the pipe. When you kill it, it will just wash away out through your faucets; just make sure you remove your aerators in order not to clog them.

  1. Shut off the water supply line to your water heater.
  2. Drain some water out of your water heater from the drain valve.
  3. Disconnect the supply line from your water heater, so you can pour your bleach in from there.
  4. Reconnect your water heater and run hot water out all your faucets until you can smell the bleach.
  5. After letting it sit for a sufficient amount of time, flush all the water out of your hot water pipes and water heater until no more bleach is detected.

This will kill your algae, but you may still have it inside your pipes. You might need to tap on the pipe to knock it loose before flushing.

In my case I drained the pipe and the algae dried up and fell from the pipe. Or you could remove and replace the affected area.

Niall C.
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gene
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Translucent containers that hold water tend to grow algae. This is because of the constant moisture and the light getting through...an ideal environment for algae to grow. Since there's nothing you can do about the moisture, I recommend using a non-translucent tubing (such as the red or blue) for your water lines.

Shane
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Probably algae growth, as Shane says, however there's a much easier fix than replacing it: insulate it. (which is something that you probably should've done anyways!)

Michael
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Maybe this will help: http://www.mass.gov/dep/water/drinking/color.htm

Green Water

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.

isherwood
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Scott Bruns
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Are you on well water? Have you had the pH of you water tested – whether you are on well or city water? Lower pH water is corrosive to copper pipes. Seeing that you have part copper piping in your installation, the green you are seeing may be leaching from the copper pipes. Hot water also allows the leaching to occur even more than cooler water. This may explain why you are seeing it in the hot water tubing and not the other.

Also, use caution in pouring chlorine bleach into your PEX pipes. This may weaken the pipes, same as exposure to sunlight. Do your research before using bleach!

Niall C.
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Kevin
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It actually has to do with your brass fitting, these fittings are corrosive when attached to copper.

BMitch
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ju ju
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I'm a plumber and have encountered this on a few occasions. I believe it is a combination of opportunities for algae to grow in your pipes. Check the reservoir; it starts there and adds all the elements for the algae to thrive then be transported to you where, in areas it collects light and warmth to add to its growth.

Cover any pipes that are transparent to any degree of light. Without light you limit its ability to continue growing. Introduce a fine micron strainer that can be rinsed and reused, before it gets to the pressure regulator for the geyser. This has worked for me.

Niall C.
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Donovan
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This happened because of build up in the hot water heater and hard water in the area. Remember if they re-pipe your home and never replaced the heater, the old junk from the old pipes is still setting on the bottom of the water heater.

"replace heater if it's over 6 years old or do nice flush if it's under 6 years"

Niall C.
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user12638
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