Or they added that section later.Concrete is fairly inert once dry, so I would suspect thin wall copper combined with acidic water supply = pinholes.

An application of Sodium Percarbonate PerOxyhydrate will help neutralize the uric acid and the heat will open up the pores of the concrete with the extraction pulling the materials out.

Several other shocking pictures were found down there including the whole crawl space was covered in white dust which looked like Boric Acid. 

I can build an addition for about 120k that contains two "units" of 2bd/2.5ba each with lots of premium features (9.5' ceilings, acid-stained colorful concrete floors, radiant heating throughout, central air, LED lights, granite countertops, subway tile backsplash, carrara marble porcelain look-alike bathrooms, etc.)

Invest in a black light and a probe to detect uric acid crystals to identify where pets have pee-ed and where they may be marking their territory. 

It can be tested for by using nucleic acid probe molecules for detecting Naegleria species , NFOW1 or NFOW2 specifically,but takes days to sample and test.

IMHO, any type of acid wash or glaze would be totally experimental...It looks like it's pretty clean, but if not some good old TSP should handle any soot.

Salt Water corrodes a car like battery acid.

A typical electric water heater can make it 30 years easy if you just change the rods, unless you have super acidic water. 

Supposedly, these MAY last many many years over the traditional mechanical adhesion with acid.