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Hydrostatic Test

Also called: hydrostatic testing, static test

🚿 Plumbing — a term you may see in your inspection report.

What is a hydrostatic test?

A hydrostatic test plugs the drain system and fills it with water to see whether it holds — a way to check for leaks in drain lines running under a slab. Like a sewer scope, it is not part of a standard TREC home inspection and is performed by a licensed plumber. It's typically ordered when there's a specific reason to suspect an under-slab leak, and it normally requires the seller's permission, because the test itself carries a small risk to older pipe.

What it checks
Whether under-slab drain lines hold water
Part of a TREC inspection?
No — a licensed plumber performs it
When it's ordered
When there's reason to suspect an under-slab leak
Requires permission
Yes — normally the seller's, due to the small risk involved

What it actually is

The drain system gets sealed and filled. If the water level drops, something down there is leaking. It's a direct test of the thing you can't see.

Why it matters in East Texas

The reason this comes up here is our soil. An under-slab leak keeps a patch of clay permanently wet, and permanently wet clay under one part of a slab is exactly the recipe for uneven foundation movement.

What I do when I find one

This is outside what I perform. What I do is tell you when the evidence — foundation movement in a specific area, unexplained moisture, a water bill that doesn't match usage — suggests it's worth asking a plumber about.

What it means for you

Because it needs seller permission and a plumber's schedule, this is a first-week-of-the-option-period item, not a last-day one.

More plumbing terms: Polybutylene Pipe · Cast Iron Drain Line · Galvanized Supply Pipe · TPR Valve · Sewer Scope

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90-Day Inspection Warranty

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