A general home inspection covers plumbing in about fifteen minutes. The inspector runs the faucets, flushes the toilets, notes the water heater’s age and moves on. That is enough to catch a dripping tap. It is not enough to catch the three problems that cost Houston buyers real money after closing: a failing sewer line, a slab leak, and supply pipe that is at the end of its life inside the walls. All three are invisible from a bathroom, and all three can be found in an afternoon if you know where to look.
Here is what to check yourself on the second viewing, what to ask for during the option period, and when to pay a plumber to look before you commit.
Start with the year the house was built
In Houston the construction date predicts the plumbing better than anything else, because builders used the same materials across whole subdivisions in the same years.
| Built | Supply pipe likely | Drain pipe likely | What that means for a buyer |
| Before 1960 | Galvanized steel | Cast iron under the slab, clay to the street | Both are at or past their service life; budget a repipe and a sewer camera |
| 1960 to 1975 | Galvanized or early copper | Cast iron, clay or early PVC | Cast iron drains often channelled; roots in clay laterals |
| 1975 to 1995 | Copper, or polybutylene from about 1978 | PVC | Polybutylene fails at the fittings and insurers dislike it; copper may have pinholes |
| 1995 to 2010 | Copper or CPVC | PVC | Generally sound; check the water heater and fixtures |
| 2010 onward | PEX | PVC | Builder-grade heaters and fixtures reaching replacement age around year 10 |
None of this condemns a house. It tells you which tests below matter most for the one you are looking at.
Test 1: Read the water heater
Find the label on the tank. The serial number encodes the manufacture date; most manufacturers put the year in the first or second pair of digits, and the inspector’s report will translate it. A tank heater in Houston lasts eight to twelve years; the hard water shortens the top end. A heater over ten years old is a replacement in the first year or two of ownership, and that belongs in the negotiation.
While you are there: rust streaks down the tank, water or rust in the drain pan, a pan with no drain line, a tank in an attic with no pan at all, a relief valve pipe that has been capped, and a gas heater in a closet with no vents in the door are all notes for the repair list. Run the hot water at the nearest tap and time how long it takes to arrive; a long wait tells you about pipe routing, not the heater, but it is worth knowing.
Test 2: Turn on everything at once
Run the shower, the bathroom sink and the kitchen faucet together, then flush a toilet. If the shower drops to a trickle, the house has a pressure or pipe-size problem, which in older Houston homes usually means galvanized steel supply lines that have narrowed with rust from the inside. Galvanized pipe was standard here into the 1960s and shows up in 1970s houses too. It does not get better, and partial repairs tend to disturb the next joint.
Look under the kitchen sink and in the water heater closet for the pipe itself. Grey threaded metal is galvanized. Copper is copper. White or cream plastic is PVC or CPVC. Grey flexible pipe with copper or plastic crimp fittings in a house from the late 1970s to the mid 1990s is likely polybutylene, which insurers often flag and which fails at the fittings. Red and blue flexible pipe is PEX, which is modern and fine. If the house has galvanized or polybutylene, a repipe is in its future; repipe specialists in Houston can quote it from a walk-through during the option period, and that quote is the negotiation.
Test 3: Fill and drain
Fill the tub and the bathroom sink, then let them go at once while watching the toilet. Gurgling from the toilet, or water rising in the shower drain, points to a main line that is partly blocked or sagging. Slow drains in every fixture at once is the same signal. One slow sink is a clog; everything slow is the sewer.
Flush each toilet and watch whether it rocks when you lean on it. A toilet that moves has broken its wax seal and has usually been leaking under the floor for months.
Test 4: Walk the yard
Look for a sewer cleanout, a capped 3- or 4-inch pipe near the foundation or at the property line. A house with no cleanout is a house where every future drain job starts by pulling a toilet, and often a house whose line has never been cleaned from outside. Look for unusually green or soft patches of lawn in a dry week, which can mean a leaking water line or a leaking sewer. Mature trees between the house and the street, especially live oaks, are a flag for root intrusion in the sewer lateral, the most common sewer repair in Houston’s older neighborhoods. Note the backflow preventer on the irrigation if there is one; cracked brass means a past freeze.
Test 5: Check the meter with the house quiet
Make sure every faucet, appliance and the irrigation are off, then look at the water meter at the street. If the small leak indicator or the last digits move over ten minutes, water is leaving the system somewhere, and in a slab-foundation home that somewhere is often under the floor. A warm patch on a tile floor, a water bill the seller cannot explain, or a water heater that runs when nothing is on are the other signs.
A moving meter is not a reason to walk away; it is a reason to find out what it is before you own it. Professional leak detection in Houston isolates the hot, cold, yard and drain lines by pressure and locates the leak with listening equipment, so the repair is a known number instead of a guess. That number, in hand before the option period ends, is leverage.
Test 6: Open every cabinet and look up
Under every sink: staining on the cabinet floor, swollen particleboard, a smell of damp, mineral crust on the shutoff valves, supply lines that are chrome-plated rigid tubes rather than braided stainless. Each is small on its own; several together say the plumbing has not been maintained.
In every room: ceiling stains, especially under upstairs bathrooms and under attic water heaters. Sellers paint over stains; look for a patch that is slightly brighter than the rest of the ceiling.
In the attic, if you can get there safely: the water heater pan and its drain, insulation on exposed pipes, and the condition of the vent stack flashing.
Test 7: Read the disclosure, then ask the questions it does not answer
The Texas seller’s disclosure asks about plumbing defects, previous repairs and water penetration. Read every yes. Then ask the questions the form does not: when was the water heater replaced, has the sewer line ever been cleaned or repaired, has there been a slab leak, does the house have a cleanout, and has the house ever flooded. A seller who has lived with a sewer that needs cabling every spring will not always think of it as a defect; a receipt for annual drain cleaning is a disclosure in itself.
The red-flag table
| What you found | How serious | Next step |
| Water heater over 10 years old | Routine | Budget a replacement; negotiate a credit |
| Galvanized or polybutylene supply pipe | Significant | Repipe quote during the option period |
| Every drain slow, gurgling, big trees, no cleanout | Significant | Sewer camera inspection before the option period ends |
| Meter moving with everything off | Significant | Leak detection; repair quote |
| Warm floor spot, heater runs constantly | Significant | Leak detection; expect a slab leak |
| Toilet rocks | Minor to moderate | Lift and inspect the flange and floor; cheap unless the floor is soft |
| Ceiling stain under a bathroom or attic heater | Moderate | Find the source; may be an old, fixed leak or a current one |
| Seized shutoff valves, old supply lines | Minor | Replace them in the first month |
When to pay for a plumber before closing
Three situations justify a plumber’s visit during the option period, separate from the general inspection:
- The house was built before 1980 and the sewer line has never been camera-inspected. A sewer camera inspection shows the inside of the lateral from the house to the street, on video, and finds roots, cracks, bellies and collapsed sections with the distance marked. It is the single most valuable plumbing test a buyer can order in Houston, and the video becomes a negotiating document.
- Anything in tests 2 or 5 came back bad: low pressure, a moving meter, galvanized or polybutylene pipe. Each of those is a four-figure repair at minimum, and a quote in hand changes what you offer.
- The home has been vacant or flipped. Vacant homes develop dried-out traps, seized valves and water heaters that have sat cold; flipped homes have new fixtures on old pipe, and the new tile may be hiding the drain problem that prompted the sale.
Each visit is a few hundred dollars against repairs that run into the thousands. Ask for the findings in writing with photos; sellers and their agents take a plumber’s report more seriously than a buyer’s observation.
What to negotiate, and how
A repair credit is usually better than a seller-managed repair, because the seller will choose the cheapest contractor and you will own the result. For a sewer line, a repipe or a slab leak, get the quote from a plumber you would actually hire and ask for that amount. For a water heater past ten years, ask for the replacement cost even if it still works; it is a matter of when. For small items, the seized valves and old supply lines, let them go and fix them yourself in the first month.
The short version
- Water heater over ten years old: budget a replacement.
- Galvanized or polybutylene pipe: budget a repipe, eventually, and get the quote now.
- Everything draining slow, gurgling, no cleanout, big trees: order a sewer camera inspection.
- Meter moving with the house quiet: order leak detection before the option period ends.
- Read the disclosure for what it says, and ask about what it does not.
From the trade
Plumbers see the houses that buyers wish they had checked. Royal Flush Affordable Plumbing, a Houston company that has worked on homes across the city since 2007, sees the same pattern in older neighborhoods from Meyerland to the Heights: the finishes are new, the pipe behind them is original, and the sewer line has never been looked at. An hour of testing during the option period changes what you pay, or what you walk away from.