If you're replacing your RV water heater, you've got a decision to make: stick with a traditional tank unit, or upgrade to a tankless system? Both have real advantages — and real trade-offs. The right choice depends on how you camp, how many people are in your rig, and what you're willing to spend.
This guide breaks down exactly how each type works, compares them side by side, and helps you decide which one makes sense for your setup.
How Each Type Works
Tank Water Heaters
A traditional RV tank water heater works just like the one in your house — on a smaller scale. A tank (typically 6 or 10 gallons) is kept at a set temperature at all times. When you open a hot tap, pre-heated water flows out and cold water enters the tank to be heated for next time. Most RV tank heaters run on propane, shore power (120V electric element), or both (DSI/electric combo units).
The trade-off: once you've used the hot water in the tank, you wait for it to reheat — typically 20–30 minutes for a 6-gallon unit.
Tankless Water Heaters
A tankless (on-demand) water heater has no storage tank. Cold water flows through a heat exchanger and is heated instantly as you use it. There's no standby heating, no tank to run out of, and no recovery wait time. Tankless RV units run on propane and require a 12V DC power source for the ignition and controls.
The trade-off: a more involved installation, especially if you're replacing a tank unit, and no 120V electric heating option on most models.
Tankless vs Tank RV Water Heater: Side-by-Side Comparison
| Feature | Tank Water Heater | Tankless Water Heater |
|---|---|---|
| Hot Water Supply | Limited (6 or 10 gallons) | Unlimited (on-demand) |
| Recovery Time | 20–30 minutes | Instant |
| Propane Usage | Higher (heats continuously) | Lower (heats only when needed) |
| Upfront Cost | $400–$800 | $350–$800 |
| Installation Difficulty | Easy (direct swap) | Moderate to difficult |
| Unit Size / Weight | Larger, heavier | Compact, lighter |
| Power Required | Propane and/or 120V AC | Propane + 12V DC |
| Winterization | Standard RV bypass | Must fully drain heat exchanger |
| Lifespan | 10–15 years | 15–20 years |
| Best For | Solo/couple campers | Families, full-timers, boondockers |
Pros and Cons of Tank RV Water Heaters
Pros
- Simple installation: Replacing a tank unit is usually a direct swap — same cutout, same connections
- Works on electric: Many tank heaters have a 120V electric element, so you can heat water on shore power without burning propane
- Familiar operation: Simple thermostat dial, no learning curve
Cons
- Limited hot water: 6 gallons goes fast with two or more people showering
- Standby propane use: The tank stays heated even when you're not using it, burning propane around the clock
- Recovery wait: Once the tank is depleted, you're waiting 20–30 minutes for more hot water
Pros and Cons of Tankless RV Water Heaters
Pros
- Unlimited hot water: No tank to run out of — the water stays hot as long as the propane flows
- Better propane efficiency: Only burns propane when you're actively using hot water
- Longer lifespan: Tankless units typically outlast tank heaters by several years
- Space savings: More compact footprint, which matters in tight RV bays
Cons
- Installation complexity: Retrofitting a tankless unit into a tank water heater bay often requires new venting, different cutout dimensions, and rewiring
- No electric backup: Most tankless RV units are propane-only — no 120V electric element option
- Winterization: The heat exchanger must be fully drained and blown out — a standard bypass valve alone isn't sufficient
Cost Comparison
Here's a realistic breakdown of what you're looking at for each option:
| Cost Factor | Tank Water Heater | Tankless Water Heater |
|---|---|---|
| Unit Cost | $400–$800 | $350–$800 |
| Installation (DIY) | Low — direct swap | Moderate — may need new venting/wiring |
| Installation (Pro) | $100–$200 | $200–$400+ |
| Ongoing Propane Cost | Higher (standby heating) | Lower (on-demand only) |
| Long-Term Value | Good for occasional campers | Better for frequent/full-time use |
For occasional campers who use their RV a few weekends a year, the price difference between tank and tankless is much smaller than most people expect — making the decision less about budget and more about how you camp. For full-timers or frequent campers, the propane savings from a tankless unit can still tip the scales in its favor over time.
Who Should Choose a Tank Water Heater?
A tank water heater is the right call if:
- You camp solo or as a couple with modest hot water needs
- Your RV has a standard 6-gallon cutout and you don't want to modify it
- You frequently use shore power and want the electric heating option
- You camp occasionally rather than full-timing
Who Should Choose a Tankless Water Heater?
A tankless water heater makes more sense if:
- You travel with family or groups where multiple people need hot showers
- You boondock frequently and want to conserve propane
- You're a full-timer who wants the best long-term efficiency
- You're doing a significant renovation and don't mind a more involved installation
- You've already had to wait for hot water one too many times and it's driving you crazy
Our Top Picks
Best Tank Water Heater — Suburban SW6DE
The SW6DE is the gold standard for RV tank water heaters. It runs on propane and 120V electric (or both simultaneously), fits the standard 6-gallon cutout, and is backed by Suburban's reliability reputation. It's the most popular replacement unit we carry.
Best Tankless Water Heater — Fogatti Instashower 7
For tankless, the Fogatti Instashower 7 is one of the most popular choices among RV owners right now — and for good reason. It delivers 1.58 GPM of continuous hot water on demand, runs on propane with 12V DC ignition, and installs into a standard 6-gallon cutout without major modification. It's a strong pick for families, full-timers, and boondockers who want true on-demand performance without the complexity of a larger retrofit.
Frequently Asked Questions
Can I replace a tank RV water heater with a tankless unit?
Yes, but it's not always a direct swap. Tankless units often have different dimensions and venting requirements. Measure your existing cutout carefully and check compatibility before ordering.
Do tankless RV water heaters work on electric?
Most do not. The majority of tankless RV water heaters are propane-only and use 12V DC power only for ignition and controls — not for heating. If you rely heavily on shore power, a tank unit with an electric element may be a better fit.
How much propane does an RV tankless water heater use?
Because tankless heaters only fire when hot water is flowing, they typically use 30–50% less propane than a tank unit that maintains temperature around the clock. Actual usage varies by how often hot water is used.
Is a 6-gallon RV water heater enough for two people?
For two people who are mindful of water use, a 6-gallon tank is workable — but tight. Short Navy showers are a must. If you find yourselves frequently waiting for the tank to reheat, it may be time to consider upgrading to 10 gallons or going tankless.
What is the best RV water heater brand?
Suburban and Atwood (now sold under the Dometic brand) are the two dominant brands in RV water heaters. Both are reliable and well-supported with available replacement parts. Suburban tends to be the most widely stocked and easiest to find replacement parts for.
Ready to Upgrade Your RV Water Heater?
Whether you're replacing a worn-out tank unit or making the switch to tankless, The RV Surplus carries both at discount prices with free shipping to the continental U.S.
Shop RV Water Heaters at The RV Surplus →
Need help choosing the right model? Call or text us at 574-218-0549 and we'll help you find the right fit for your rig. You can also browse our RV Water Heater Troubleshooting Guide if you're not sure whether you need a repair or a full replacement.
Still on the fence? Our team knows RV water heaters inside and out — don't hesitate to reach out before you buy.