Most homeowners asking about repiping are focused on one thing: the pipe that just leaked. But a whole-house repipe is a fundamentally different scope of work, and understanding what it actually covers can save you from making a costly decision you’ll regret two years down the line.
The short answer is yes. A proper whole-house repiping project in Houston should replace both hot and cold water supply lines. But the longer answer is more useful, because not every contractor scopes the job the same way, and knowing the difference matters a lot when you’re comparing quotes.
What a Whole-House Repipe Actually Covers
When a repipe specialist talks about replacing your water supply lines, they mean the entire network of pipes that carries pressurized water from your main shutoff to every fixture in the home. That network has two branches running through most of the house: cold water, which feeds every fixture, and hot water, which feeds most of them after running through your water heater.
Both branches are made of the same pipe material in most Houston homes built before the 1990s, typically galvanized steel or copper. Both corrode. Both fail. And both run through the same walls, ceilings, and slab.
Replacing only one set would be a bit like replacing the bald tires on one axle of a car and leaving the worn ones on the other. You’ve done work, but you haven’t solved the problem.
Cold Water Lines
The cold supply line enters your home from the municipal main or well, passes through the meter and shutoff valve, and then branches out to every fixture: toilets, hose bibs, kitchen sink, dishwasher, every bathroom, and the water heater inlet. It carries untreated water at full line pressure, which in Houston can run between 60 and 80 PSI depending on the neighborhood.
In older galvanized systems, cold lines tend to show the earliest signs of failure, including rust-colored water, mineral buildup that chokes the pipe from the inside, and pinhole leaks at elbows and threaded joints.
Hot Water Lines
Hot lines branch off from the water heater outlet and run to most of the same fixtures, minus the toilets and most hose bibs. Because hot water is more chemically aggressive and is constantly cycling between high and lower temperatures, hot lines in copper systems often develop pinhole corrosion faster than cold lines.
A home with failing hot water pipes will typically show low pressure at the shower and kitchen faucet first, since those runs are longest. Homeowners often assume it’s the water heater. Frequently, it’s the pipe.
Why Both Lines Must Be Replaced Together
There’s a practical reason repipe specialists replace both hot and cold lines in the same visit: they’re already in the walls.
Access holes are cut, furniture is moved, drywall is opened. Running both sets of new pipe while the wall cavities are accessible takes less time and labor than doing them separately. A contractor who replaces only the cold lines today and leaves the hot lines in place is guaranteeing you another disruption, another round of drywall work, and another bill within a few years.
More importantly, the root cause of failure in most Houston homes is the age of the material, not the temperature of the water running through it. If your cold galvanized lines are showing corrosion after 30 or 40 years, your hot galvanized lines have been aging under the same conditions. They will fail.
Reputable Houston plumbing companies will always scope a whole-house repipe to include both hot and cold supply lines, from the main shutoff to every fixture in the home.
The Material Makes a Difference: PEX-A vs. Copper vs. Galvanized
Once you’ve confirmed that both lines are being replaced, the next decision is what they’re being replaced with. This is where homeowners often feel lost, and it’s worth understanding the basic options.
Galvanized Steel
This is what most pre-1985 Houston homes were built with. It corrodes from the inside out over time, accumulating rust and mineral deposits that restrict flow and eventually cause leaks. No reputable contractor should be replacing your pipes with galvanized steel today.
Copper
Copper was the standard upgrade for decades and is still a solid material. It’s durable, heat-tolerant, and has a long track record. The downsides: it’s expensive, rigid (which means more fittings and more potential failure points), and susceptible to pinhole corrosion in homes with aggressive water chemistry, which is common in parts of the Houston area.
PEX-A (Cross-Linked Polyethylene, Peroxide Method)
PEX-A is the material most repipe specialists are now using for whole-house replacements, and for good reason. It’s flexible enough to run longer continuous runs with fewer fittings, which reduces the number of joints where leaks can develop. It handles freeze-thaw cycles better than rigid pipe, which matters during the rare but brutal Houston cold snaps like the February 2021 storm. And it has a projected service life of 50 years or more under normal residential conditions.
Uponor PEX-A, specifically, is widely regarded as the premium product in this category. Its expansion-fitting connection method creates joints that are actually stronger than the pipe wall itself, which is a meaningful structural advantage over crimp or clamp connections used with lesser PEX types.
A Houston repiping specialist familiar with the local water supply conditions and the age profile of Houston neighborhoods will typically recommend Uponor PEX-A for both hot and cold line replacements as the most durable long-term solution.
What About Supply Lines to Individual Fixtures?
There’s a distinction worth clarifying here. The main repipe covers the in-wall supply lines, the trunk lines and branch lines running through your home’s structure. The short braided or chrome “supply lines” that connect from the shutoff valve stub-out under a sink or toilet to the fixture itself are a separate component.
In most repipe projects, those short final connections are replaced as part of the job since the shutoff valves are already being addressed and the connection points are open. Confirm this with your contractor before signing anything.
The same applies to shutoff valves. Many older Houston homes have angle stops and main shutoffs that are original to the house and long overdue for replacement. A thorough repipe should include new shutoff valves at each fixture location.
What the Repipe Process Looks Like from Start to Finish
Understanding the sequence of a professional repipe helps set expectations and reduces anxiety. Here’s how a well-run project typically unfolds:
- Assessment and estimate: A specialist visits to count fixtures, assess the current pipe condition, and quote based on fixture count, not home size or location.
- Permits pulled: A licensed contractor pulls the required permits before work begins. This protects you and ensures the work is inspected.
- Access holes cut: Small openings are made in drywall to reach pipe runs. The number and size of holes depends on your home’s layout and the routing required.
- Old pipe removed, new pipe installed: Both hot and cold lines are run simultaneously. The new PEX-A is flexible enough to snake through walls with fewer access points than rigid copper.
- Pressure testing: Once the new lines are connected, the system is pressure-tested before walls are closed.
- Drywall repair and paint: A contractor who includes drywall repair and paint matching in the scope, which not all do, will restore the walls before leaving.
- Final inspection: The permit inspection confirms the work meets code.
Water is typically restored at the end of each working day, with most standard homes completed in one to two days total.
How Houston’s Water Supply Affects Pipe Longevity
Houston draws water from both surface sources like Lake Houston and groundwater via the Gulf Coast Aquifer. The resulting water chemistry varies across the metro. Some areas have harder water with higher mineral content, which accelerates scale buildup inside older galvanized and copper pipes. Others have slightly more corrosive water that speeds up the pinhole failure common in copper systems.
According to the Water Quality Association, hard water affects roughly 85% of American homes, and the Houston metro sits squarely in that category for many zip codes. That context matters when choosing pipe material: PEX-A is non-reactive to water chemistry in a way that metal pipe isn’t, which is part of why specialists favor it for long-term residential installations.
Repipe Solutions Inc has completed more than 10,000 repipes across the Houston area, including homes in The Woodlands, Katy, Sugar Land, Kingwood, Pearland, and Cypress, which gives the team a detailed working knowledge of how local water chemistry and pipe age interact across different neighborhoods.
Key Takeaways
- A legitimate whole-house repipe replaces both hot and cold water supply lines, not just one set.
- Both lines run through the same wall cavities, so doing them together saves time, labor, and future disruption.
- PEX-A is widely considered the superior replacement material for Houston homes, especially Uponor PEX-A with its expansion-fitting connections.
- The repipe scope should include new shutoff valves at fixture locations, pressure testing, permits, and ideally drywall repair and paint.
- Houston’s water chemistry, particularly in harder-water zones, accelerates pipe degradation in both galvanized and copper systems, making material selection more than an afterthought.
Frequently Asked Questions
Does a whole-house repipe include the pipes going to my water heater? Yes. The cold supply line feeding the water heater inlet and the hot line running from the outlet are part of the supply system and should be included in the repipe scope. Confirm this with your contractor before work begins, especially if your water heater is being replaced at the same time.
Will my water be off the entire time the repipe is happening? Most professional repipe crews restore water at the end of each working day. A standard single-story or two-story Houston home typically involves about 5 to 6 hours of downtime per day during the project, which usually wraps within one to two days total.
How do I know if my hot or cold lines are the ones failing? Often both are failing simultaneously in an older home, even if the symptoms point to one side. Rust-colored water and low pressure at hot fixtures suggest hot line issues, while brown water at cold taps and low pressure everywhere points to the cold supply. A licensed repipe specialist can assess both systems during an on-site estimate.
Is PEX-A safe for hot water lines? Yes. PEX-A is rated for use in both hot and cold water applications. Uponor PEX-A, specifically, carries ratings for continuous use at temperatures up to 200 degrees Fahrenheit at 80 PSI, well above the operating range of any residential water heater.
Do I need permits for a whole-house repipe in Houston? Yes. A whole-house repipe is a permitted project in Houston and the surrounding municipalities. A licensed plumbing contractor will pull the permits before work starts and coordinate the required inspection. Never agree to a repipe that skips the permit process. It creates serious issues for resale and insurance claims.
Wrapping Up
For any Houston home with plumbing that’s 25 years old or older, the question isn’t usually whether to repipe, it’s how to do it right. Making sure both hot and cold lines are replaced, using the right material, by a contractor who handles permits, pressure testing, and wall restoration, is what separates a real solution from another round of patch repairs.
Take time to understand exactly what a quote covers before agreeing to anything. A detailed scope protects you more than any promotional offer.