Tankless vs. tank water heaters: honest pros & cons

We install both, so we have no horse in this race. Here's the honest comparison we give at kitchen tables all over San Antonio.

The case for a tank

A conventional 40- or 50-gallon tank is the cheapest way to make hot water: lower unit cost, simpler install, and any plumber can service one. If your current tank is plumbed and vented correctly, a swap is usually a same-day job.

• Upfront cost: typically a third to half the installed price of tankless.
• Simplicity: fewer parts, cheaper repairs, no annual descaling requirement.
• Recovery, not flow: a tank doesn't care how many fixtures run at once — until the stored hot water runs out.

The case for tankless

A tankless unit heats water only when a tap opens, so there's no standby loss and no running out — the shower is hot for as long as it runs.

• Endless hot water: the big one for large families and soaking tubs.
• Lifespan: 20+ years with maintenance, versus 8–12 for a tank.
• Space: hangs on a wall; frees up a garage corner or a closet.
• Efficiency: real savings, though the gas bill delta alone rarely pays for the conversion.

In our hard water, an unsoftened tankless needs a descale flush every year. Skip it and the warranty — and the heat exchanger — suffer.

The conversion catch

Going from tank to tankless isn't just swapping boxes. Tankless burners are big — often 150,000+ BTU — so many conversions need a larger gas line, new venting, and a condensate drain. That's why the installed price gap is wider than the sticker price gap.

Our honest rule of thumb

Replace like-for-like if the budget is tight, the household is small, or the current setup works fine. Go tankless if you regularly run out of hot water, plan to stay in the house ten-plus years, and will actually keep up the annual flush — or pair it with a softener and forget about it. Either way, get the sizing done with a real fixture count, not a guess.