Before you assume the worst, a few checks narrow down what’s going on — and give you the right words to describe it when you call. Symptoms map to causes surprisingly well on water heaters.

No hot water at all

Gas tank: the pilot may be out, or the gas control valve or thermocouple has failed. If you smell gas, don’t relight anything — leave the area and call your gas utility first.
Electric tank: check the breaker; a tripped high-limit reset or a failed heating element is next most likely.
Tankless: check for an error code on the unit’s display and note it — it tells the technician a lot.

Some hot water, but it runs out fast

Sediment buildup eating tank capacity — common in Central Texas’ hard water.
A failed dip tube mixing cold water into your hot supply.
On electric tanks: one of the two elements is out — you get half a tank.

Water is discolored, smelly, or the tank is noisy

Rusty water from the hot side only, rotten-egg smell, or rumbling and popping sounds all point at the tank itself — sediment and corrosion. A rumbling tank isn’t dangerous by itself, but it’s a tank telling you how it will fail.

Water around the base — act now

A leaking tank doesn’t heal. Turn off the cold-water shutoff above the heater and its power (breaker for electric, gas valve to “off” for gas), and call right away. JB Plumbing answers 24/7 — a tank that fails at 2 AM doesn’t wait for morning.

Note what the unit is doing — no heat, half heat, noise, or a leak — and whether it’s gas or electric. Those two facts get you an accurate answer on the phone.