Pressure, the one nobody checks
The healthy range is 50-75 psi. Above 80, every joint, valve, seal and appliance connection in the house is under more stress than it was designed for — permanently.
It is the most common preventable cause of leaks and the least investigated, because high pressure feels like a good shower rather than a problem.
The usual source is a pressure-reducing valve that has drifted. They last 10-20 years and then fail in one direction or the other. Occasionally it is thermal expansion in a closed system, producing spikes rather than constant high pressure.
A gauge on an outdoor hose bib costs very little. Take a reading during the day and again overnight, when municipal pressure often rises — the overnight figure is what your plumbing actually endures. More in high water pressure.
Worth knowing
The components high pressure kills first are the braided supply lines behind toilets and under sinks, and rubber washing machine hoses. Those fail as a burst rather than a drip, and they are usually behind something where nobody sees them.
Corrosion, and what your pipe material tells you
Galvanized steel corrodes from the inside. The bore narrows over decades and rust enters the water. If a house still has galvanized supply, its remaining life is measurable rather than theoretical.
Copper is long-lived but develops pinholes, particularly on hot lines and particularly on hard water. Once one appears, others usually follow in the same run — they are the same age under the same conditions.
Polybutylene (grey, blue or black flexible plastic, 1978-1995) becomes brittle and fails at the fittings, often without warning and often inside a wall. Some insurers will not write a policy on a house that still has it.
PEX is what most modern work uses and is not meaningfully affected by our water chemistry.
Softening the water genuinely slows this, because scale and corrosion accelerate each other. It is not the reason most people buy a softener, but it is a real part of the return.
Ground movement, which is a local speciality
Expansive clay swells when it takes on water and shrinks when it dries out, and our weather runs that cycle hard — long dry summers broken by heavy rain.
Anything buried has to absorb that. Over years it pulls joints apart, drops sags into lines laid to fall correctly, and stresses pipe running through or under a slab.
You cannot prevent the soil moving, but you can reduce how much moisture swings: keep gutters clear and discharging away from the house, maintain a grade that sheds water away from the foundation, and avoid letting irrigation soak one side of the house while the other bakes.
That last one is more significant than it sounds. Uneven watering around a foundation produces uneven soil movement, which is exactly what stresses buried pipe.
Temperature
Freezing is the obvious one, and here it does disproportionate damage because our houses are not built defensively — supply lines run through vented attics, exterior walls and open crawl spaces. Full prevention list in pipe freeze prevention.
Thermal cycling is the quiet one. Copper expands as it heats and contracts as it cools, several thousand times a year. Where a hot line rests against concrete, rebar or a joist, that movement abrades it.
This is why hot lines fail before cold ones, and why slab leaks are nearly always on the hot side. It is also why proper pipe support and isolation matter during installation — a line that can move without rubbing lasts far longer.
Catching a leak early
Most of the cost of a leak is what it does before anyone notices, so detection is worth more than repair skill.
Run the meter test twice a year. Shut off everything that uses water, check whether the meter's flow indicator moves, and compare readings an hour apart. Ten minutes, and it finds leaks with no visible symptom — method in finding a hidden leak.
Check under sinks monthly with a torch, looking for a slow drip or the white mineral crust left by one that evaporates between visits.
Compare bills against the same month last year, not last month. Summer irrigation hides a genuine leak for an entire season otherwise.
Which repairs are reasonable to do yourself
Reasonable: replacing a supply line to a toilet or faucet, replacing a compression washer or cartridge, tightening a slip nut on a trap, swapping rubber washing machine hoses for braided stainless.
Not reasonable: anything inside a wall or slab, anything requiring soldering, anything on the gas side, and anything where you cannot shut the water off first.
Explicitly not: pipe repair tape, epoxy putty or a clamp as a permanent fix. They are legitimate as a way to hold something overnight until it can be repaired properly — and they get treated as solutions, at which point the pipe fails somewhere less convenient with nobody expecting it.
The test for whether to call: if you cannot see the whole leak, you do not yet know what you are repairing.