7 Best 10 GPM Electric Tankless Water Heaters of 2026

The Eemax HA036240 is a powerhouse in the electric tankless water heater space—designed for homes that demand uninterrupted hot water under heavy load. With a massive 36 kW heating capacity and engineered for commercial-grade durability, this unit delivers up to 10 GPM under optimal conditions, making it one of the few models capable of supporting multiple simultaneous showers and high-demand appliances in larger households. Its robust copper-nickel heating elements and precision modulating technology ensure rapid response to flow changes, eliminating the dreaded cold-water sandwich that plagues lesser units. For users tired of lukewarm showers during peak usage, this heater is a game-changing solution.

In real-world testing, the HA036240 excels in cold climate installations, where incoming groundwater temperatures dip below 50°F. Thanks to its high temperature rise capability, it maintains 120°F+ output even at 6–7 GPM, a feat most 27–30 kW units struggle with. It’s built for whole-home coverage, easily handling back-to-back showers, dishwasher cycles, and laundry—all without a drop in performance. However, its power demands are extreme: requiring 3 x 60A breakers and 200A+ service, it’s not suitable for older electrical panels or DIY installs. While it lacks Wi-Fi or smart controls, its industrial-grade reliability and consistent output make it ideal for performance-focused buyers who prioritize raw power over app integration.

Compared to the Rheem RTEX-24 and ECOTOUCH 27kW models, the Eemax stands in a higher performance tier—offering 33% more heating power than the 27kW units and significantly better flow under high delta-T conditions. It’s not the most energy-efficient or compact option, but for large homes, multi-family units, or cold-weather regions, it’s unmatched in sheer delivery. While the ECOTOUCH and Rheem models offer smart features and easier installation, the Eemax HA036240 is the clear choice when maximum flow and reliability are non-negotiable—delivering luxury-level performance that justifies its premium positioning.

The Rheem 18kW 240V strikes a compelling balance between performance, reliability, and user-friendly design, making it a standout mid-range contender. Its self-modulating heating system dynamically adjusts power output based on flow rate and inlet temperature, ensuring consistent hot water without energy waste. With a 4.4 GPM maximum flow, it’s well-suited for small to medium homes, handling two fixtures—like a shower and kitchen sink—without issue. The external digital thermostat with ±1°F accuracy gives users precise control, eliminating guesswork and reducing scalding risks—a major pain point with analog dials.

During real-world testing, the Rheem 18kW proved responsive and stable, especially in moderate climates where ground water stays above 55°F. It heats water to 120°F at around 3.2 GPM, enough for simultaneous bathroom and kitchen use. The copper immersion heating elements are field-serviceable—a rare and valuable feature that extends lifespan and reduces long-term costs. However, in colder regions, its lower kW rating limits flow, dropping below 2 GPM for full-temperature rise. Installation is straightforward thanks to bottom 3/4″ NPT connections, but it still requires a 40A double-pole breaker and 8 AWG wiring, so electrical compatibility is key.

Against the MIZUDO 14kW and Westinghouse 11kW models, the Rheem offers superior flow and modulation, making it better for multi-point use. While it lacks Wi-Fi, its digital display and real-time feedback provide more control than basic units. It doesn’t match the high-output Rheem RTEX-24 or Eemax HA036240, but for homeowners seeking dependable performance without overspending on power, it’s an excellent middle ground. It delivers more hot water, better tech, and longer service life than budget units, with a simpler install than 24kW+ models.

The Westinghouse APOLO-11k redefines convenience for small households and tech-savvy users with its built-in Wi-Fi and voice control—a rare feature in this price range. Delivering up to 2.6 GPM, it’s optimized for point-of-use or single-bathroom applications, eliminating cold waits and temperature swings during showers. Its smart app integration with Alexa and Google Assistant allows remote temperature adjustments in 1°F increments, making it ideal for users who want personalized comfort without manual tweaks. The separated water-electric pathways and 4-layer safety system ensure long-term reliability and peace of mind, especially in older homes.

In testing, the APOLO-11k shines in apartments, tiny homes, and under-sink installations, where space and simultaneous demand are limited. It heats water in under 3 seconds and maintains stability within ±2°F during normal use. The compact 14.2” x 9.5” footprint mounts flush to walls, freeing up utility space. However, its 11kW output struggles in cold climates, delivering only 1.5–1.8 GPM at full temp rise, making it unsuitable for large showers or multiple fixtures. While the LED display and app provide excellent feedback, the unit requires a 50A breaker and 8 AWG wiring, which may be overkill for its output—posing a hurdle for some electrical panels.

When compared to the MIZUDO 14kW and ECOTOUCH 27kW, the Westinghouse trades raw power for smart functionality. It can’t match the flow of higher-kW units, but for renters or small-space dwellers who value app control, it’s unmatched. It’s less powerful than the Rheem 18kW but offers greater automation and voice integration—a trade-off that makes sense for tech-first users. While others deliver more hot water, this heater delivers smarter, more personalized control in a compact, safety-certified package.

The Rheem RTEX-24 is engineered for high-flow performance, delivering up to 6.5 GPM under ideal conditions—making it one of the most capable all-electric tankless heaters for whole-home use. Its 24kW modulating system adjusts power in real time to maintain consistent temperature across multiple fixtures, even during back-to-back showers. The digital temperature display with 1°F precision gives users granular control, while the on/off dial simplifies operation compared to touchscreens prone to glitches. For families tired of scheduling showers, this unit offers true simultaneous hot water freedom—without the lag or dropouts common in lower-tier models.

In real-world scenarios, the RTEX-24 performs exceptionally well in moderate to warm climates, where it can support three bathroom fixtures at once. It achieves 120°F output at 4.5 GPM with 55°F inlet water, outperforming 18kW and 14kW competitors. However, in colder regions, performance drops significantly, requiring users to limit flow or accept lower temps. Installation demands are steep: 3 x 40A breakers and 200A service are mandatory, ruling out older homes. While it lacks Wi-Fi, its proven modulation and durable build make it a favorite among contractors for reliable, maintenance-free operation.

Against the ECOTOUCH 27kW and Eemax HA036240, the RTEX-24 sits in the sweet spot of power and practicality. It doesn’t match the 36kW Eemax’s output, but it’s easier to install and more efficient for average homes. Compared to the ECOTOUCH, it lacks a touch panel but offers Rheem’s trusted reliability and simpler interface. It delivers higher flow than mid-tier models while avoiding the extreme electrical load of 30kW+ units, making it the best choice for performance-focused homeowners with modern electrical systems.

The ECOTOUCH ECO270S delivers exceptional value with smart features, combining 27kW power, self-modulation, and a sleek touch panel at a fraction of the cost of premium brands. With a 5.5 GPM flow rate, it supports 2–4 usage points—perfect for small homes or apartments needing reliable hot water for showers, sinks, and dishwashers. Its advanced self-modulating system adjusts power in real time based on flow and temp, saving up to 60% on energy bills compared to tank heaters. The user-friendly touch screen displays real-time status and allows 1°F adjustments, offering control typically found in higher-end models.

In testing, the ECO270S proved responsive and efficient, maintaining stable temperatures even when flow fluctuated. It handles two showers or a shower plus kitchen use in moderate climates with ease. The 3/4″ NPT connections simplify plumbing, and the separated water-electric pathways reduce corrosion risk, enhancing longevity. However, it demands 3 x 40A breakers and 200A service, which may not fit older panels. While it performs well, the build quality isn’t as robust as Rheem or Eemax, and customer support is less established—something to consider for long-term ownership.

Compared to the Westinghouse APOLO-11k, the ECO270S offers more than double the flow and power, making it suitable for larger households. Against the Rheem RTEX-24, it matches performance while adding a more modern interface and better energy savings. It lacks the Eemax’s brute force but delivers smarter modulation and better efficiency at a lower price. For buyers who want high performance, smart features, and energy savings without breaking the bank, this heater offers the best overall value in its class.

The ECOTOUCH ECO270B is a champion of energy efficiency, leveraging its 27kW self-modulating system to deliver 5.5 GPM of instant hot water while slashing energy use by up to 50% compared to traditional tank heaters. Its adaptive power draw ensures only the necessary energy is used—reducing waste when flow is low or temperature rise is minimal. The digital display and touch controls make setup intuitive, with real-time feedback on status and settings, eliminating the learning curve of basic models. For eco-conscious homeowners, this heater offers maximum comfort with minimum environmental impact.

In real-world use, the ECO270B maintains stable output across two bathrooms or a kitchen and shower combo, especially in regions with mild groundwater. It heats water to 120°F at over 4 GPM, outperforming lower-kW units. However, like all electric models, it struggles in very cold climates, requiring flow reduction to maintain temperature. Installation demands are significant: 113A draw, 3 x 40A breakers, and 200A service—making it unsuitable for older homes. While it lacks Wi-Fi, its internal safety suite (leakage, overheat, dry-fire protection) and ETL/UL certification ensure safe, long-term operation.

Against the MIZUDO 14kW, the ECO270B offers nearly double the flow and far superior efficiency. Compared to the Rheem RTEX-24, it matches performance but adds better energy modulation and a more modern interface. It doesn’t have the Eemax’s 36kW firepower, but for most homes, its optimal balance of power, efficiency, and cost makes it the smarter long-term investment. It delivers more savings, better control, and comparable flow—making it the top pick for energy-focused buyers.

The MIZUDO 14kW is a budget-friendly powerhouse, delivering 3.4 GPM of instant hot water in a compact, wall-mounted design—perfect for small homes, apartments, or point-of-use installations. With 98% energy efficiency, it heats water in under 3 seconds and can cut electricity costs by up to 60% versus traditional tank models. Its LED digital display and ±1°F temperature stability—powered by a chip that adjusts 20,000 times per second—ensure buttery-smooth showers without fluctuations. For cost-conscious buyers, it offers premium features at an entry-level price.

In testing, the MIZUDO handled shower and sink use simultaneously with ease in moderate climates. It maintains 120°F output at 2.5 GPM, making it ideal for one-bathroom homes. The 60A breaker and 6 AWG wiring requirement are manageable for most modern panels, and the 1/2″ NPT connections simplify plumbing. However, in colder regions, flow must be reduced to avoid lukewarm output. While it lacks Wi-Fi and app control, its built-in safety suite (leakage, over-temp, dry-fire protection) and ETL certification ensure safe operation. Customer support is responsive, a rare plus in this price range.

Compared to the Westinghouse 11kW, the MIZUDO offers 30% more flow and better temperature control at a slightly higher cost. Against the Rheem 18kW, it sacrifices some power but wins on price and space savings. It doesn’t match the ECOTOUCH 27kW’s output, but for tight budgets and small spaces, it’s unbeatable. It delivers more flow, better tech, and greater efficiency than most sub-$250 heaters—making it the best value for cost-sensitive buyers.