If you have a water meter you can turn off all water use in the house and watch the meter for an hour and see if it moves.

916;
This can become a bottomless pit for you. Regardless of the reason you elect to pay for 1/2 the repairs, any high speed attorney will twist it into an admission of responsibility. What happens if the repair is 15K? You did admit you felt responsible. Not a verbal admission, but a check written. Next month they find termites, a leaking roof or whatever. Could the aforesaid high speed attorney make his case? Maybe yes, maybe no. The type of questions they'll hit you with are "how many times did you suggest the home inspection"?"If you felt a HI was that important, why didn't you insist, or offer to pay for it"? "YOU did claim they were a valuable client, sent you referals, gave you a Christmas present, yet you balked at 300"? A sharp, even a dull attorney may well cast enough doubt to get some monetary consideration. Also, they're the inexperienced and poor home buyer. You're the well trained and wealthy realtor. All these darn courts know is half each if your right and punitive damages if you're wrong. Plus thoudsands in attorney fees for you.
If you want to keep them happy, don't offer until they ask and then tell them your corporate council won't allow it. Bummer, you don't want your broker to fire you.
The short version...no way. It wasn't your stupidity that caused this.
Just another observation here. A diagnosis of a leaking hot water line and an estimate of $3,000 based on a warm floor is the most Mickey Mouse trouble shooting I've ever seen. In New England they used to build slabs with the water and heat lines in the slab. When a pipe developes a leak there's water all over the floor and no way of determining which room the leaking pipe is. The water travels along the pipes until it reaches a crack. Mickey flippin Mouse.

Oh, I have a headache from this one! I always have my buyers sign the FHA For Your Protection, Get A Home Inspection form whether they have a home inspection or not. It shows proof that we discussed one; plus, alot of REO sellers are requiring it even if it's stated in plain English on the contract that the buyers are having a home inspection.

Own personal experience last year: Mother-in-law's water bill was fairly high, $74 whereas she checked with her neighbors who have the same number of bodies in household and theirs were $28 (two different neighbors). We shut off the MAIN shut off valve inside the house, then opened the water meter in the ground, waited a few minutes, and observed the needle was still moving. Ugh! Had a guy from a few counties over come down with a listenening device. This guy actually pinpointed the leak to within one inch! Her house had that "Blue" piping (Google it) that was recalled a number of years ago, but you had to file an application for replacement within a certain period of time and of course M-i-L did not know she had that piping (couldn't see it because it was covered under the concrete floor in basement as it was used just for the main water pipe). Perhaps you can find one of these guys online (like I did). His company is Line Locators in Virginia if you'd like to see his website.

One plumber wanted to do the same - route piping overhead (easier for them, but which meant ripping out drywall and reinstalling, plus the ceiling would end up lower in the hallway). M-i-L didn't like that. At least with the concrete being torn up (another plumber made repairs, not replacement), it was easier to fix, and, I figure if it leaks again, at least only the lower half of the basement may get wet versus leaking from the ceiling into the walls and then the carpet. Ugh!

If it's a concrete slab, there is probably no way a regular home inspector could have found it. Even then, they are usually only obligated up to the cost of the inspection itself - they make buyers sign that acknowledgement.

Your buyers SHOULD have purchased a home warranty - next time offer it to your buyers as your "gift" at settlement. Why didn't you suggest it as part of seller concessions? Most sellers will gladly pay for one. At least you'll feel a little better when a repair is needed that they don't have to shell out as much cash with a home warranty.

Repairs are part of homeownership - sad, but true and I tell my buyers that.

And I wholly agree with everyone who has responded - helping to pay for repairs can be construed as if you were in some way responsible.

A referral is one thing; an actual sold transaction is another.

Good luck to you!

Just from personal experience - I bought a house 18 years ago in Jacksonville, had a home inspection and a home warranty.
About a year later, we had a "slab leak" under the dining room floor and we knew it because it ran into the garage and the living room that was about 5 inches or so lower than the dining room.
They ended up having to jackhammer the floor and found the leak at a T fitting where the water line branched to the kitchen and the water heater which was in the garage.

The plumber who did the work said it was fairly common in the Jax area because when the houses were built the piping was copper but the fittings were an alloy. The hole in the fitting was just slightly larger than a pin hole.

I never blamed the sellers or tried to get recovery from our real estate agent. Sometimes things just happen. Think about it, you buy a car and a month later the battery dies. Is it the fealer's fault or the car salesman fault? Would you go back to try to get a new battery from them?

Too late now; but couldn't they have come up with a more attractive name for that kind of foundation than . . . . "The Slab" ?

I know, I know . . . . there's the "Floating Slab" and we have the "Insulated Slab" to dress it up a little bit.

We sometimes have frost get into the ground and lift the slab, kind of crooked-like, and then it's called "A Heaving Slab" or sadly, a "Busted-Up Slab" which you have to be careful with in communicating to the more delicate minds among us.

Hey, how about a Slab of Spam with that Lettuce and Tomato ?

But I digress.

Interesting to read how you act of generosity can set you up for a slippery slop of trouble.

I agree with the others you earned your money keep it. The only thing you should offer is some advice to get a 2nd opinion based upon what we've learned about plumbing here.