What are the most common plumbing problems in older Phoenix homes?

The single most notorious problem material in homes of this era is polybutylene. It is a grey plastic supply pipe, often stamped PB2110, installed in millions of homes from about 1978 to mid-1995. It was cheap and quick to run, so it shows up a lot in the building boom that built much of metro Phoenix.

The trouble is chemistry. Chlorine in city water reacts with the pipe over time and makes it brittle. The material flakes from the inside, then cracks and fails, often at the fittings first. Phoenix disinfects its water with chlorine, so the conditions that degrade polybutylene are present in every tap here.

Because the failure is built into the material, you cannot fix it by patching one leak. The whole system is aging at once. InterNACHI notes the broad scope of the problem: "By some estimates, between 6 and 10 million homes had polybutylene plumbing installed during this time period." The standard recommendation is full replacement, not spot repair. For more on replacing it, see our page on whether you should replace polybutylene pipes.

Two older metals fail in older Phoenix homes, and they fail in opposite halves of the system.

Galvanized steel supply pipe was common in homes built before the 1960s. The zinc coating wears off and the steel corrodes from the inside, narrowing the bore with rust and scale. That shows up two ways: low water pressure that gets worse over years, and brown, red, or yellow water, especially first thing in the morning. Once flow is restricted, the pipe is at the end of its service life. The usual fix is to repipe with copper or PEX.

Cast iron drain pipe is the other side of the house, the drain and waste lines. It was common in homes built before the mid-1970s. Cast iron rusts and cracks from the inside over decades. Per the InterNACHI life-expectancy chart, cast iron waste pipe lasts roughly 50 to 60 years, so pipe from the 1960s and early 1970s is now at or past that mark. Warning signs are slow or recurring drain clogs, dark water coming up from drains, and sewer odor inside. Failed cast iron is replaced with PVC or ABS. Our cast iron drain pipe lifespan page goes deeper on the timeline.

A note on lead: the EPA states that lead can enter drinking water from corroding pipe and from old solder. Pre-1986 plumbing solder was leaded, and lead particles can attach to the surface of galvanized pipe over time. If your home has old galvanized supply or pre-1986 joints, that is a reason to have your water tested. The EPA is the authority to rely on here, not a plumber.

Phoenix is slab-on-grade country. Most homes sit on a concrete slab with no basement, and in many of them the copper supply lines run inside or under that slab. When a buried copper line develops a leak, it is called a slab leak. The general causes are the things that act on any buried copper line over time: corrosion, abrasion where the pipe rubs against concrete or rebar, and movement in the soil beneath the slab. Hard water and shifting desert soil are part of the picture. Signs include a warm spot on the floor, the sound of running water with everything shut off, an unexplained jump in the water bill, and damp or buckling flooring. Our page on why slab leaks are common in Arizona covers detection and repair.

Out in the yard, the sewer lateral is the line that carries waste from the house to the city main, and you the homeowner own it. Two problems are common in older homes. The first is root intrusion, where tree roots find a joint or crack and grow into the pipe, snagging waste and causing backups. The second is Orangeburg pipe, a fiber-and-tar pipe used into the early 1970s that delaminates, goes oval, and collapses with age. If your line is Orangeburg, it is at or past the end of its life and should be planned for replacement.

Beyond the pipe in the walls, the fixtures and the water heater in an older home are often original or close to it. Old toilets can use up to 6 gallons per flush against a modern 1.28 gallon standard, and old faucets, valves, and shutoffs wear out, stick, or weep. Tank water heaters generally last about 6 to 12 years, so a unit in a house that has not been updated is usually living on borrowed time.

The common thread across every problem on this page is hard water. The USGS classifies water above 180 mg/L as "very hard," and the City of Phoenix reports total hardness in the range of roughly 170 to 284 mg/L, which puts it at the top of "hard" and into "very hard." That mineral load builds scale inside pipes, water heaters, and valves. Scale narrows pipe, coats heating elements, and shortens the life of every appliance the water touches. It does not cause the failures above by itself, but it speeds them all up, which is why older Phoenix plumbing tends to wear out a little faster than the textbook lifespans suggest.

You cannot judge an older home's plumbing from the faucet handles. The pipe that matters is hidden in walls, the slab, and the yard. A few checks tell you most of what you need to know.

• Identify the supply pipe material. Look at exposed runs in the garage, under sinks, and at the water heater. Grey pipe stamped PB2110 is polybutylene. Dull grey magnetic pipe is galvanized steel. Reddish pipe is copper, and flexible color-coded pipe is PEX.
• Note the water heater's age. The manufacture date is coded into the serial number on the label.
• Watch the water itself. Brown or yellow water and pressure that has slowly dropped over the years point to corroding galvanized supply lines.
• Get a sewer scope. A sewer scope is a camera inspection of the lateral from the house to the city tap. InterNACHI notes it is not part of a standard home inspection and is an add-on service. It reveals root intrusion, cracks, bellies, and whether the line is Orangeburg or cast iron, all before you own the problem.

If you are buying, order the sewer scope and ask the inspector to confirm the supply-pipe material. If you already own an older home, a camera inspection of the drain and sewer lines, paired with a look at your supply material, turns guesswork into a plan. Call HQ Plumbing & Air at (602) 675-1555 to have the lines scoped and the system assessed.