10 Best Tankless Water Heaters With Leak Detection for 2026: Smart Picks for Every Home

Tankless water heaters can deliver hot water on demand while using less space than traditional storage tanks, but leak protection is an important part of a safe installation. The right model depends on whether you need point-of-use service for one sink or enough capacity for multiple fixtures.

This roundup compares 10 electric and gas options across compact under-sink designs and higher-capacity whole-home systems. Use the buying guide below to match flow rate, power requirements, controls, and leak-related safeguards to your plumbing setup.

Best 10 Tankless Water Heaters with Leak Detection Picks for 2026

Best Whole-Home Gas Pick – Rheem RTG 9.5 GPM WiFi Tankless Heater

For shoppers comparing tankless water heaters with leak detection, the Rheem RTG Series combines whole-home capacity with WiFi connectivity and the LeakGuard Leak Detection and Prevention System. Its 9.5 GPM output and 199,900 BTU rating are designed for larger households with multiple hot-water demands.

Best For: Large families and multi-bathroom homes needing indoor natural-gas water heating.

Pros:

• 9.5 GPM capacity supports approximately 3-4 simultaneous showers.
• LeakGuard leak detection and prevention system adds monitoring and protection.
• WiFi control, built-in freeze protection, and flame-failure protection.
• Includes a 15-year heat-exchanger warranty and 5-year parts warranty.

Cons:

• Requires professional installation and an indoor direct-vent setup.
• Uses natural gas, so it is not suitable for homes without a gas connection.

This is a strong choice when whole-house flow and leak-related safeguards matter more than simple installation. Its wall-mounted design also helps conserve utility-room floor space.

Best Under-Sink Electric Value – ThermoMate 4.5kW Point-of-Use Heater

The ThermoMate SS-45 is a compact point-of-use option for buyers seeking tankless water heaters with leak detection-related design features. While it does not list an electronic leak-detection system, its separated heating element and water line, stainless-steel water tube, and IP25 waterproof construction are intended to support durability in under-sink installations.

Best For: Sinks, small businesses, salons, and other point-of-use applications.

Pros:

• Compact 10.95-by-7.4-by-2.52-inch design fits tight spaces.
• Self-modulating 4.5kW heating system delivers up to 0.85 GPM at a 35°F rise.
• Separated cast-aluminum heating element and water line help reduce scale and corrosion exposure.
• Digital touch controls adjust temperature in 1°F increments.

Cons:

• Designed for point-of-use service rather than whole-home demand.
• Requires hardwiring, a 40A double-pole breaker, and minimum 8 AWG wire.
• Its notes do not specify a dedicated leak-detection or automatic leak-shutoff system.

This model makes sense when you need fast hot water at one sink and have the electrical capacity for installation. Buyers specifically requiring leak alarms or automatic shutoff should verify those features before purchase.

Best Built-In Leak Shutdown – Rheem Prestige 11 GPM Condensing Heater

The Rheem Prestige RTGH-RH11DVLN stands out among tankless water heaters with leak detection because its water and gas leak detection system can shut down the unit and provide an error code. It also pairs an 11 GPM flow rate with built-in recirculation for high-demand indoor applications.

Best For: Large homes that prioritize leak-related shutdown protection, recirculation, and high flow.

Pros:

• Water and gas leak detection can shut down the unit and display an error code.
• 11 GPM flow rate supports substantial household hot-water demand.
• Built-in recirculation helps provide hot water with less waiting and waste.
• Auto-Learn programming tracks usage and adjusts to peak hot-water needs.

Cons:

• Indoor natural-gas installation requires appropriate professional setup.
• Its larger whole-home configuration may be more than a small household needs.

For shoppers who place leak-response capability at the top of the list, this Rheem offers the clearest protection feature in the lineup. The condensing design, recirculation, and high flow also make it a capable whole-home replacement.

Best Compact 240V Option – CAMPLUX 6kW Under-Sink Heater

The CAMPLUX TE06ProN2 is a small electric point-of-use heater for sinks, apartments, offices, and other limited-demand locations. It does not list a dedicated electronic leak detector, but its notes describe a separated water line, auto-shutoff overheat protection, and a no-leaking design feature.

Best For: Compact sink installations and small households with a suitable 240V electrical circuit.

Pros:

• 6kW self-modulating system provides instant hot water for point-of-use needs.
• Compact wall-mounted design suits apartments, tiny homes, and offices.
• Features auto-shutoff overheat protection and a separated water line.
• Touch controls show water temperature and inlet flow in real time.

Cons:

• Requires hardwiring, a 30A circuit breaker, 10 AWG wire, and 1/2-inch NPT connections.
• Point-of-use capacity is not intended for high-demand whole-home service.
• The notes do not identify a dedicated leak alarm or automatic leak-detection shutoff.

This is a practical space-saving choice when a 240V circuit is available and the goal is fast hot water at a sink. If leak detection is essential, confirm whether the listed no-leaking feature meets your desired level of protection.

Compact Multi-Fixture Pick – Rheem 8kW Tankless Electric Water Heater

For shoppers comparing tankless water heaters with leak detection, the Rheem RTEX-08 stands out with a listed 5-year leak warranty and compact, point-of-use design. Its 8kW output can provide up to 1.95 GPM, making it a practical choice when the electrical requirements and intended demand are properly matched.

Best For: Smaller homes or multi-fixture applications that have suitable 240V electrical service.

Pros:

• Listed 5-year leak warranty and 1-year parts warranty.
• Digital thermostatic control adjusts in 1-degree increments from 80°F to 140°F.
• Compact design is about 90% smaller than a traditional tank water heater.
• Heats water only when a hot water tap is turned on.

Cons:

• Requires 240V single-phase power, a 40-amp double-pole breaker, and #8 AWG copper conductors.
• The recommended minimum 100-amp household service may limit installation options.
• Its output is limited to up to 1.95 GPM.

The RTEX-08 is a space-saving option with useful temperature control and explicit leak-warranty coverage. Confirm sizing and electrical capacity before choosing it for multiple simultaneous fixtures.

Under-Sink Space Saver – CAMPLUX 4.5kW Point-of-Use Heater

Among tankless water heaters with leak detection considerations, this CAMPLUX point-of-use model offers dry-combustion protection and a 2-year limited warranty in a very small wall-mounted package. Its 120V, 4.5kW design is intended for one sink rather than broad household demand.

Best For: A single sink in a kitchen, wet bar, school, salon, boat, or other space-constrained location.

Pros:

• Compact 10.95-by-2.52-by-7.4-inch design fits small spaces.
• LED digital display and touch controls simplify temperature adjustment.
• Self-modulating operation adjusts power based on flow rate and temperature setting.
• Dry-combustion protection is listed as a special feature.

Cons:

• Designed for only one sink and has a 1.0 GPM temperature rise of 50°F.
• Must be hard-wired; it does not use a plug.
• Requires a 40A circuit breaker, 10 AWG wire, and a 1/2-inch NPT water connection.

The CAMPLUX is a focused solution for fast hot water at one fixture, especially where installation space is limited. Its modest output and dedicated electrical requirements make careful application matching important.

Whole-Home Capacity Pick – Rheem 18kW Tankless Electric Water Heater

For buyers evaluating tankless water heaters with leak detection, the Rheem RTEX-18 pairs a whole-home 18kW configuration with a listed 4.4 GPM flow rate. It uses self-modulation to adjust power to hot-water demand and includes external digital temperature control.

Best For: Whole-home installations needing more capacity than a small point-of-use heater can provide.

Pros:

• Up to 4.4 GPM flow rate for broader household use.
• Self-modulating operation adjusts power to hot-water demand.
• External digital control provides approximately 1-degree temperature accuracy.
• Copper immersion heating elements are field serviceable.

Cons:

• The supplied notes do not list a leak-detection feature or leak-specific warranty.
• An 18kW, 240V configuration may require substantial electrical planning.
• Its larger 14.5-by-18.25-inch footprint requires more wall space than compact point-of-use units.

The RTEX-18 is the strongest capacity choice in this group, with useful controls and serviceable heating elements. If leak detection is a priority, verify the exact protection and warranty details before purchase.

Best Low-Flow Pick – Compact 120V Under-Sink Heater

If you need tankless water heaters with leak detection for one sink, this compact 3kW plug-in model offers a practical point-of-use solution. Its knob-controlled LED display, leakage protection, and 30–55°C temperature range make it straightforward for light-duty applications.

Best For: Low-flow hot water at a single kitchen, bathroom, laundry, office, or utility sink.

Pros:

• Leakage, overheat, dry-heating, and over-pressure protection.
• Simple control knob with LED temperature display.
• Compact 7.1 × 9.8 × 2.8-inch wall-mounted design.
• Provides on-demand warm water without preheating.

Cons:

• Designed for low-flow use only and is not suitable for showers.
• Cannot supply multiple taps simultaneously.
• Its 3kW, 120V output may provide limited warmth depending on flow and inlet temperature.

This is a sensible choice when space and installation simplicity matter more than high flow. For showers or broader household demand, a higher-wattage hard-wired model is more appropriate.

Best Higher-Flow Option – 14kW 240V Electric Heater

For shoppers comparing tankless water heaters with leak detection for showers or multiple fixtures, this 14kW electric model offers substantially more capacity than compact under-sink units. It delivers up to 3.38 GPM, includes leakage protection, and uses precise electronic temperature control.

Best For: Homes needing on-demand hot water for two to three points of use, such as a bathroom and kitchen.

Pros:

• Up to 3.38 GPM with claimed three-second instant heating.
• Leakage, over-temperature, and dry-heating protection.
• ETL certified with water-electricity separation technology.
• LED display and temperature control from 86°F to 140°F.

Cons:

• Requires hard wiring, a 240V/60A two-pole breaker, and 6 AWG wiring.
• The household panel should have at least 150 amps of total capacity.
• Professional electrical installation may be necessary.

This is the strongest fit of the three for higher-demand use, provided your electrical system can support it. Verify panel capacity, wiring, breaker requirements, and water connections before purchase.

Best 110V Value – Digital Under-Sink Water Heater

This 110V model is a useful option if you want tankless water heaters with leak detection for a compact sink installation. It combines a digital display, water-electricity isolation, IPX4 protection, and automatic shutoff features in a wall-mounted design.

Best For: Low-flow kitchen, bathroom, apartment, RV, or camping applications where 110V power is preferred.

Pros:

• Leakage, dry-boil, overheating, and inactivity shutoff protection.
• ETL-standard design with water-electricity isolation.
• LED display with Fahrenheit or Celsius settings.
• Compact installation with standard 1/2-inch NPT connections.

Cons:

• Not suitable for showers, which normally require at least 1.8 GPM.
• Must be installed vertically; horizontal installation is not allowed.
• Requires appropriate wiring and a trip switch rated over 32A.

Choose this unit for point-of-use convenience and a 110V installation, not for whole-bathroom or multi-fixture demand. Follow the supplied installation guidance carefully, including vertical mounting and sealed pipe connections.

How We Picked These Tankless Water Heaters with Leak Detection

We selected models across the main categories shoppers consider: gas units for whole-home demand, high-output electric heaters for multiple fixtures, and compact point-of-use models for sinks or remote bathrooms. We also considered rated power, flow capacity, installation requirements, temperature controls, safety features, certifications, and whether the design includes built-in monitoring or compatible leak-detection protection.

Product listings can use “leak detection” to describe different features, so verify the exact specification before buying. Some heaters detect abnormal flow or internal leaks, while others require a separate water sensor, shutoff valve, drain pan, or smart-home accessory.

Quick Comparison

Best For	Typical Type	What to Prioritize
One sink or remote fixture	3–4.5kW electric	Low flow activation, simple controls, compact installation
Kitchen or bathroom group	6–14kW electric	240V service, adequate GPM, temperature stability
Several simultaneous fixtures	18kW electric or gas	Higher flow, electrical capacity or gas ventilation
Fast hot-water delivery	Recirculating gas model	Built-in recirculation, controls, professional installation

Key Buying Factors

Flow Rate and Temperature Rise

Flow rate is measured in gallons per minute, but the usable output depends on incoming water temperature and the temperature increase required. A small heater may work well for handwashing but struggle with a shower. Estimate how many fixtures may run at once, then choose a model with enough capacity rather than relying only on the maximum advertised GPM.

Electrical or Gas Requirements

Compact 110–120V units are convenient for a single point of use. Larger electric heaters commonly require a 240V circuit, substantial amperage, and sometimes multiple breakers or upgraded wiring. Gas units need correctly sized gas lines, venting, combustion air, condensate handling where applicable, and professional installation.

Leak Detection and Safety

Look for clear information about leak sensing, automatic shutoff, over-temperature protection, dry-fire protection, pressure relief, and error alerts. A built-in sensor is useful, but it does not replace proper installation. For added protection, pair the heater with a compatible floor or pipe sensor and an automatic main-water shutoff, especially near finished floors or in an attic.

Controls, Maintenance, and Warranty

Digital displays and precise temperature adjustment make commissioning easier, while diagnostic codes can simplify troubleshooting. Gas models may need periodic vent and burner maintenance; electric units should be inspected for scale, loose connections, and filter blockage. Check warranty terms, required professional installation, replacement parts, and local service availability before purchasing.

Who Should Buy Which Tankless Water Heaters with Leak Detection?

Choose a compact 110–120V or 3–4.5kW unit for a single sink, office, workshop, or low-demand bathroom. Select a 6–14kW 240V model when serving a kitchen or limited combination of fixtures, provided your electrical panel can support it. For larger households and simultaneous showers, an 18kW electric unit or a high-capacity gas heater is usually the better fit. Buyers who want faster delivery at multiple fixtures should consider a gas model with recirculation, while anyone prioritizing simple installation should focus on point-of-use electric designs and confirm leak-protection compatibility before ordering.