Identify the pipe material first: galvanized steel is dull gray and magnetic, copper is reddish, PEX is flexible and color-coded, polybutylene is gray and stamped PB2110. Then read the water heater serial number to date it, and watch for rusty water, low pressure, and leaks.
How do I identify the pipe material and its era?
Look at the exposed pipe under sinks, at the water heater, and along garage, attic, or basement runs, then match the color, feel, and markings. Each material was common in a known stretch of years, so the material alone narrows the home's plumbing age.
- Galvanized steel looks dull gray, feels hard, and is magnetic (a fridge magnet sticks). It was used in homes from about 1930 onward and is the oldest supply pipe you are likely to find still in service.
- Copper is reddish-brown, like a penny, and turns green where it corrodes. It has been used from the early 1900s to today, so copper alone does not date a home, but its condition tells you plenty.
- PEX is a flexible plastic tube, usually color-coded red for hot, blue for cold, and white for either. It bends around corners, and it has been in homes since about 1985, so PEX means at least part of the system is fairly modern.
- CPVC is rigid plastic, cream or tan, and is glued at the joints rather than soldered. It is stiffer and lighter than copper.
- Polybutylene is gray (sometimes blue or black outdoors), flexible, and stamped "PB2110." It was installed from 1978 to 1995.
A magnet and a flashlight settle most cases in minutes. If you can see a basement or attic run, you also catch mixed systems, where an old galvanized house was partly repiped in copper or PEX.
| Material | Look and feel | Typical era | Quick test |
|---|---|---|---|
| Galvanized steel | Dull gray, hard | About 1930 on | Magnet sticks |
| Copper | Reddish, green if corroded | Early 1900s to now | Not magnetic, soft sheen |
| PEX | Flexible, red/blue/white | About 1985 on | Bends by hand |
| CPVC | Rigid, cream or tan | Recent decades | Glued joints, plastic |
| Polybutylene | Gray, flexible | 1978 to 1995 | Stamped PB2110 |
Why does polybutylene matter so much?
Polybutylene is the one material worth flagging the moment you spot it, because it fails from the inside. The gray PB2110 pipe was a cheap, fast option for two decades, but chlorine and other oxidants in normal tap water make it brittle over time, and the fittings can crack with little warning. It is no longer an approved material, and inspectors treat it as a known liability rather than a normal pipe.
If you find the gray PB2110 stamp, plan on replacement regardless of how it looks today. A pipe that appears fine can split without a visible warning sign, which is exactly why it was the subject of large class-action settlements that re-plumbed hundreds of thousands of homes. When you are buying, polybutylene is a real bargaining point. When you already own it, budgeting for a repipe is the safe call.
How do I date the water heater from its serial number?
Find the rating plate on the side of the tank and read the serial number, because manufacturers encode the build date inside it. The format differs by brand, so you match the serial against the maker's key. InterNACHI keeps a brand-by-brand chart for exactly this, and notes that knowing a heater's age helps you anticipate failure rather than wait for a flood.
A few common patterns: many brands start the serial with the month and year or the week and year (for example, a serial beginning with a date code points to that month or week of manufacture). Some use a letter for the month. Because the codes are not standardized, write down the full serial and the brand, then check the chart for that manufacturer. As InterNACHI puts it in its water heater dating guidance, "Most manufacturers use the first four digits to designate the month and year of manufacture."
Age sets your expectation for what comes next:
- A storage tank heater typically lasts about 6 to 12 years. In Phoenix, hard water and scale push many tanks toward the lower end of that range.
- A tankless unit often runs 10 years or more, especially when it is descaled on schedule.
A heater past its expected life is not automatically broken, but it is on borrowed time, and the rusty water or popping sounds below tell you when it is close. For matching a replacement to your household size, see our guide on what size water heater you need.
What visible signs reveal the plumbing's condition?
Age tells you the odds; the visible signs tell you what is happening right now. Walk the home and check the water, the pressure, and the metal itself.
- Discolored water. Brown, red, or yellow water, especially first thing in the morning, points to rust inside the pipes. This is the classic tell of failing galvanized steel, where the inside is corroding and shedding into the supply.
- Low or dropping pressure. When a whole-house flow weakens over time, internal corrosion and scale are narrowing the pipe. Phoenix tap water is very hard (USGS classes water above 180 mg/L of calcium carbonate as very hard, and Phoenix runs well into that range), so scale builds faster here than the textbook lifespan suggests.
- Frequent leaks. A pipe that springs a small leak, gets patched, then leaks again somewhere else is telling you the metal has thinned across the whole run, not just at one joint.
- Visible corrosion or stains. Flaking rust on galvanized pipe, or green or blue-green stains at copper joints, marks active decay. Green staining is corroding copper; rust flaking is steel near the end.
A single sign can be minor. Several together, in a home with old pipe material, point to a system that is failing rather than just aging. Our page on the signs of old, failing pipes goes deeper on reading these clues, and the page on common plumbing problems in older Phoenix homes covers what local hard water and slab construction add to the picture. One more note on metal: the EPA states that lead particles can attach to the surface of galvanized pipes and over time enter drinking water, which is another reason old galvanized supply is worth replacing rather than nursing along.
When should I get a professional inspection or a sewer camera?
Get a professional look whenever the stakes are high or the pipe is hidden, because the eye test stops at what you can see. A standard home inspection is the baseline. Under the InterNACHI Standards of Practice, a general home inspection checks the main shutoff, the water heater (energy source, venting, TPR valve, and bracing), the interior supply by running fixtures, every toilet, and functional drainage, then reports defects.
Just as important is what that inspection leaves out. The Standards of Practice say it does not include water softeners, well pumps, floor drains, sprinkler systems, concealed or underground piping, or a sewer scope. Those are separate services. So if you want to know the condition of the buried sewer lateral, a general inspection will not tell you, and you order a sewer camera instead. A sewer scope is a video inspection of the line from the house to the city tap that reveals blockages, root intrusion, cracks, bellies, and the pipe material itself. It is not part of a standard inspection, and because the homeowner owns the lateral, it protects a buyer from a hidden five-figure surprise. Our sewer camera inspection page explains how that works.
Knowing the age and condition before you sign matters for money. A buyer who spots polybutylene or 70-year-old galvanized can negotiate or walk. A seller who checks the water heater age and TPR valve ahead of listing avoids a last-minute repair scramble. And an owner who reads the signs early can budget a planned repipe instead of paying emergency rates after a burst.