{"id":780,"date":"2025-12-30T07:07:35","date_gmt":"2025-12-30T13:07:35","guid":{"rendered":"https:\/\/plumbing101.i234.me\/wordpress\/?p=780"},"modified":"2025-12-25T17:40:49","modified_gmt":"2025-12-25T23:40:49","slug":"water-in-the-den-slab-leak-or-pipe-above","status":"publish","type":"post","link":"https:\/\/plumbing101.i234.me\/wordpress\/water-in-the-den-slab-leak-or-pipe-above\/","title":{"rendered":"Water in the Den? Slab Leak or Pipe Above?"},"content":{"rendered":"

You\u2019re looking at a house as a rental.<\/p>\n

You walk in and find water in the den.<\/p>\n

The break is \u201cunderneath,\u201d but the source is unknown.<\/p>\n

It could be a supply line under the slab.<\/p>\n

It could be a drain line in the slab.<\/p>\n

It could also be a pipe above the slab.<\/p>\n

Quick Q&A<\/h2>\n

Q: If the leak is under the slab, how do you run a new water line?<\/strong><\/p>\n

A: Many plumbers abandon the bad line and run new PEX through walls or the attic, then drop down to each fixture.<\/strong><\/p>\n

Step one: confirm if it\u2019s an active supply leak<\/h2>\n

Start with one simple test.<\/p>\n

Turn off every faucet and appliance.<\/p>\n

Then watch the water meter leak indicator.<\/p>\n

If it moves, you likely have a supply leak.<\/p>\n

This helps before any demo begins.<\/p>\n

Here\u2019s a quick guide to reading the meter:<\/p>\n

How to read a water meter to catch hidden leaks<\/a>.<\/p>\n

\"Water
Water in the Den? Slab Leak or Pipe Above?<\/figcaption><\/figure>\n

Step two: figure out the hot side or the cold side<\/h2>\n

Shut off the water heater feed valve.<\/p>\n

Run a cold faucet for a minute.<\/p>\n

Watch the meter again.<\/p>\n

No movement can point to a hot-side issue.<\/p>\n

Movement can still mean cold supply.<\/p>\n

Step three: Locate the leak before choosing a repair<\/h2>\n

Slab leaks are often found with special tools.<\/p>\n

Pros may use acoustic listening or thermal imaging.<\/p>\n

That helps avoid \u201cguess and break\u201d repairs.<\/p>\n

These are common detection approaches:<\/p>\n

Ways plumbers detect under-slab leaks<\/a>.<\/p>\n

Repair choices that usually make sense<\/h2>\n

Option A: Spot repair in the slab<\/h3>\n

This is the \u201copen the slab and fix it\u201d route.<\/p>\n

It can be the lowest material cost.<\/p>\n

But access can be messy and loud.<\/p>\n

Cost varies by location and access.<\/p>\n

Some guides put many repairs in the low thousands. :contentReference[oaicite:0]{index=0}<\/p>\n

Option B: Reroute the line and abandon the old one<\/h3>\n

This is common when pipes are aging.<\/p>\n

It also helps avoid cutting the slab again later.<\/p>\n

Reroutes may run through walls or the attic.<\/p>\n

Then the plumber drops lines to the fixtures.<\/p>\n

Home cost guides often list reroutes in the hundreds to a few thousand.<\/p>\n

Option C: Partial or full repipe<\/h3>\n

This is a bigger job, but it can end repeated leaks.<\/p>\n

PEX is often used for reroutes and repipes.<\/p>\n

Some estimates put PEX repipes in the mid-thousands to five figures.<\/p>\n

What I\u2019d do before buying it as a rental<\/h2>\n