Charleston peninsula water is comparatively soft, so scale is a smaller factor here than in the outer suburbs. Downtown water heaters usually fail for other reasons.
Age and awkward siting
Peninsula heaters are often tucked into closets, attics or crawl spaces that were never designed for them, with tight clearances and difficult access. That affects both what fails and how a repair gets done, and it is why a quote given over the phone is guesswork.
Salt air and older venting
Proximity to the harbour accelerates corrosion on external components and flues. Venting installed to older standards is a genuine safety item worth checking rather than assuming.
Repair or replace
A thermostat, element or thermocouple on a tank under eight years old is generally worth fixing. A tank leaking from the body is not. In an attic installation the calculation shifts, because a failed tank there damages ceilings below — replacing a marginal unit early is cheaper than the aftermath.
Pan and drain routing
Any heater above living space needs a pan properly plumbed to a drain. A surprising number of downtown installations do not have one, and that is the difference between a puddle and a ruined ceiling.