Repair, replace, or go tankless at the lake?

The decision matrix, adjusted for well water

The standard logic — repair young units, replace old ones — still applies, but well water compresses the timeline. Mineral stress ages tanks faster, so treat a well-water unit as roughly 20–30% “older” than its birthdate suggests.

• 0–6 years, component failure: Repair. Elements, thermostats, igniters, and gas valves are maintenance events on a young tank.
• 6–8 years, component failure: Repair if the tank is sound — but have the anode checked during the visit. On a well, a spent anode at year 6 is normal, and replacing it resets the clock meaningfully.
• 8–11 years, second significant repair: The danger zone arrives earlier on well water. Two repairs in 18 months on a 9-year-old well-water tank is money toward a unit you'll buy anyway — run the replacement numbers seriously.
• 10+ years (well) / 12+ years (city), any major failure: Replace. The tank has given you its service.
• Any age, leaking tank or rusty hot water: Replace. Terminal diagnosis — no part fixes failed steel.

Protect the new unit: filtration is part of the project

Replacing a scaled-to-death tank with a shiny new one — on the same raw well, with no treatment — is how you buy the same problem twice. Budget filtration into the replacement: at minimum a whole-house sediment filter; for very hard water, a softener or scale-inhibition system. It adds to the project cost and multiplies the new unit's life. We'll test your water during the quote and recommend only what the numbers justify — not every well needs the full treatment train.

Tank vs. tankless for lake homes and rentals

Where tankless shines here

• Guest peaks. Six adults, three bathrooms, Saturday night — tankless doesn't run out. For rentals, this alone ends the most common hot-water complaint.
• No standby waste. A tank keeps 50 gallons hot for weeks between cabin visits; tankless heats only what you use. For intermittently occupied homes, the savings are real.
• Lifespan. 15–20+ years vs. 8–12 for tanks in mineral-heavy water — you may buy one tankless in the time you'd buy two tanks.
• Space. Wall-mounted in a cabin utility closet beats a floor-standing tank.

Where tankless demands respect

• Descaling is mandatory. On well water, annual descaling isn't a suggestion — skip it and the heat exchanger scales up, efficiency collapses, and warranties get voided. Budget it as an operating cost.
• Install scope. Gas or propane line sizing, venting, condensate for condensing units, freeze protection for exterior installs — the infrastructure is a real part of the quote.
• Upfront cost. Unit plus install runs well above a tank swap. The payback horizon is a decade-plus, which suits owners fine but deserves clear eyes.

Where a tank still wins

• Simple swaps. Existing footprint, venting, and fuel line? A high-efficiency tank is a half-day job at a fraction of the cost.
• Full-time residences with modest use. A couple in a lake home full-time may never recoup the tankless premium.
• Power-outage resilience. A tank of hot water stays hot through an outage; tankless needs electricity to run. Worth weighing in storm-prone lake country.

The propane factor

Many Highland Lakes homes heat water with propane, which costs more per BTU than natural gas. That tilts the efficiency math: the operating-cost gap between a standard tank and a high-efficiency or condensing unit is wider on propane, so the payback on efficiency arrives sooner. Whatever you choose, verify the propane supply — tank size, regulator, and line capacity — supports the new unit's demand, especially for tankless with its high peak draw. We check this on every propane quote; an undersized supply starves the burner and voids the point of the upgrade.

Sizing for peak, not average

Size a rental's water heater for the Saturday night, not the Tuesday. For tanks: 50 gallons is the practical minimum for a 3-bedroom rental; larger families or big soaking tubs push toward 75. For tankless: add up simultaneous fixtures (shower ≈ 2 GPM, dishwasher ≈ 1.5, washer ≈ 2) and match output at winter groundwater temperatures — well water in January is cold, which means a bigger temperature rise and lower effective GPM than the brochure rating. We do this math on every quote and show you the numbers.

What replacement costs around Marble Falls

A like-for-like tank swap — installed to code with permit, pan, expansion tank, and haul-away — typically lands in the low four figures. Tankless installs start higher and climb with fuel-line work, venting, and condensate handling. Well-water protection (filtration/softening) is a separate line item we'll quote transparently. One price, approved by you before work begins — that's the policy on every job we do.

Still in the “maybe it just needs a part” stage? Start with our Marble Falls water heater repair page for the failure-by-failure breakdown.