The Sustainability Review:
PEX Plumbing

Everything is coming together on the house rapidly; scheduling is a juggling act to optimize the time so we can move in sooner than later. This coming week (mid-December), I’m scheduled for my rough plumbing inspection, so I thought it’d be appropriate to discuss some of the basics of what we’ve done.

It’s typical for most new houses to be plumbed with copper and older ones to use anything from galvanized metal to PVC to lead. There is slowly becoming a shift to a newer material (actually it’s been around and commonly used in Europe for more than 30 years) called PEX (cross-linked polyethylene).

PEX is a plastic pipe that is flexible and made its way into the market when radiant floor heat systems became popular. It can be used for water supply lines as well as radiant heating lines in a house and there are some newer varieties that can be buried in the ground. Most plumbers now install PEX, but copper is still the most common pipe to use.

Advantages:

1. Easy to install - Even for the homeowner, you can rent/purchase tools to make the connections and it is similar to wiring a house; pull it around and bend it through nooks and crannies
2. Less likely to freeze than copper - I’ve frozen several PEX pipes that later thaw without any pipe damage, (the fittings can still freeze and break so it’s not impervious to cold weather)
3. Insulates much better than copper - If you put your hand on a hot water line that is copper it’ll be hot to the touch, PEX is significantly cooler.
4. Smaller size lines – Since PEX is easy to install, you can install a system that feeds each fixture individually, reducing the line size, making water delivery faster, and consequently wasting less water. Serving a sink with a 3/8” line is common with PEX where as copper it would be 1/2”. There is roughly half the volume of water in a 3/8” line than a 1/2” line, so the time for hot water to arrive would be reduced greatly.
5. Is impervious to acid water conditions - Our old farmhouse and our new house have acidic water, which loves to dissolve copper water lines (ever notice the greenish stains on sinks/tubs – that’s your copper pipe).
6. Cheaper to purchase and install – Copper has skyrocketed in price lately while PEX has stayed roughly the same. I read in a building magazine that it costs 30 percent less to install PEX in a development.

Disadvantages:

1. It’s plastic, and although it is technically inert and evidence shows that polyethylene doesn’t leach into your water, I’m skeptical, since we have a history of products being safe one day and not 20 years later….
2. It’s been around for 30 years but that’s it, maybe it’ll suddenly dissolve when it gets 35 years old; probably not, but there are always unknown developments with materials.
3. You can’t use it for applications above 180 degrees F over 100 psi. (boiler systems and solar hot water systems can exceed these temperatures requiring you to use copper in certain parts).
4. It’s a petroleum product that comes with a high impact price. I’m unsure of the embodied energy (total energy to produce the product from start to finish) but looking at the alternatives there aren’t many. Copper mining is right up there with oil drilling for energy consumption and environmental impact.
5. PEX is not recyclable at this point. Copper is easily recyclable.

So we installed a manifold in the basement and in about two hours pulled all the lines through the house for every fixture. There are no valves at any fixture, those are all located in one spot in the basement, just like an electrical panel. We plumbed our manifold so that fixtures like the hose bibs and toilet get rainwater directly and the rest of the fixtures get filtered water. With a manifold it would be easy to change this in the future if needed.

One other thing of note is that people have asked me if the water tastes like plastic and my answer would be no. We had PEX in our old farmhouse and have it in the yurt and have not noticed any plastic taste and that is something we pay close attention to….

Mike and his family rode out the December windstorm in their big tent (aka the yurt).

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