PEX or Copper? Choosing Pipe for a Northern Illinois Repipe

Published 2026-04-28 · updated 2026-08-25 · by Alpha Leak Fix Pros, DeKalb, IL

If a plumber has told you your house needs repiping, the next question is what to put in. Both answers are correct; they are correct in different situations, and the freeze climate here tilts the balance in a way it would not in Georgia.

The honest triggers: galvanized steel supply lines anywhere in the house, polybutylene anywhere in the house, copper with more than one pinhole, pressure that has dropped across the whole home from internal corrosion, or discoloured water that keeps returning. One repair on a system with a general condition buys months, not years.

What it is: cross-linked polyethylene, flexible, in coils. Joined with crimp rings, expansion fittings or push-fit connectors, and typically run either in a trunk-and-branch layout or home-run from a central manifold.

• It survives freezing far better. PEX expands somewhat as water inside it freezes, so a line that would split copper often survives in PEX. In a climate with a January average low near 13°F and a record of 27 below, this is not a small point.
• Fewer joints. A flexible coil snakes through joist bays and around corners with no fittings. A home-run manifold layout can put zero joints between the manifold and the fixture, and joints are where systems leak.
• Faster to install, so cheaper in labour. Usually the larger part of the difference.
• Quieter. It does not transmit water hammer and flow noise the way rigid pipe does.
• No pinhole corrosion. It is indifferent to water chemistry.

• It splits when it freezes. Rigid pipe has nowhere to go. This is the single biggest practical argument against copper in exterior walls, rim joists, garages and crawl spaces in this climate.
• Pinhole corrosion. Aggressive water chemistry, high velocity, or a run strapped too tightly all thin the wall over time.
• More joints, more labour, higher material cost.
• Noisier and more prone to water hammer without arrestors.

For most whole-house repipes here: PEX, in a home-run or trunk-and-branch layout, with copper stub-outs at fixtures and copper in the short runs immediately at the water heater. That combination gets the freeze tolerance and joint count of PEX where it matters and the heat tolerance of copper where that matters.

We lean toward copper when the run is exposed and will stay exposed, when there is a rodent concern in an outbuilding or crawl space, when the system includes a hot-water recirculation loop running continuously at temperature, or when the owner has a clear preference and understands the freeze trade-off.

Whichever material goes in, the decision that prevents the next leak is not the pipe. It is routing. A run moved out of an exterior wall into conditioned space will outlast either material, and a repipe is the one opportunity you get to fix routing for free.

We plan the new runs first, through accessible joist bays, closets and chases wherever possible rather than through finished walls. Work proceeds zone by zone — usually bathrooms first, then kitchen and laundry — so the house has water each night. Access openings are cut deliberately, kept small and placed where patching is easy. Most single-family DeKalb repipes take two to four working days, plus drywall patching and painting afterward.

Illinois requires licensed plumbers for this work, and significant alterations generally need a permit through the City of DeKalb’s Community Development Department at 164 East Lincoln Highway. We handle the permit and the inspection.