Tankless water heaters can deliver continuous hot water while using less space than a traditional storage tank, but the right choice depends on fuel type, flow rate, installation requirements, and monitoring features.
We’ve gathered 10 notable gas, propane, and electric options—including systems designed to detect leaks—so you can compare performance, efficiency, connectivity, and protection before buying.
Best 10 Tankless Water Heaters with Leak Detection Picks for 2026
Best Premium Gas Pick
Rinnai RXP199iN Smart Sense Tankless Water Heater
- 11.1 GPM output for high-demand homes
- Natural gas or propane; indoor or outdoor installation
- Built-in Smart-Circ recirculation pump
Best For: Large households wanting high-flow gas heating and recirculation
Best Dedicated Leak Protection
Floodmaster Water Heater Leak Detection System
- Leak sensor with audible alarm
- Automatic shutoff valve included
- Designed for 3/4-inch connections
Best For: Adding leak protection to a compatible water-heater installation
Best Built-In Leak Detection
Rheem RTG 9.5 GPM LP Tankless Water Heater
- Built-in LeakGuard detection and prevention
- 9.5 GPM output for 3–4 simultaneous showers
- Wi-Fi enabled indoor propane design
Best For: Families wanting integrated leak protection and high-flow propane heating
Best Electric Option
- Compact electric design needs no venting
- Advanced Flow Control maintains temperature
- Seven-year leakage warranty included
Best For: Homes with sufficient electrical service wanting compact electric heating
High-Capacity LP Pick
- 9.5 GPM flow for high-demand households
- Outdoor installation requires no venting
- Wi-Fi, freeze, and flame-failure protection
Best For: Large families and multi-bathroom homes using liquid propane
Compact Electric Choice
- Up to 5.9 GPM for multiple fixtures
- Compact, tank-free design needs no venting
- Includes a 5-year leak warranty
Best For: Electrically equipped homes seeking a compact whole-home unit
Compact Propane Pick
- 5.3 GPM output for moderate demand
- Compact outdoor propane installation
- Enhanced scale detection and Wi-Fi capability
Best For: Smaller households with limited outdoor installation space
Best Whole-Home Gas Pick
- 9.5 GPM, 199,900 BTU whole-home capacity
- Wi-Fi with LeakGuard detection and prevention
- 15-year heat-exchanger warranty
Best For: Large families and multi-bathroom homes
Best Heavy-Duty Pick
- 98% efficiency with compact wall mounting
- Wi-Fi, voice control, and temperature memory
- Four-layer protection includes leakage protection
Best For: Smaller homes and spaces with 240V service
Best High-Efficiency Propane Pick
- 9.5 GPM and 199,900 BTU whole-home output
- 0.93 UEF condensing technology
- EcoNet Wi-Fi with LeakGuard alerts and prevention
Best For: Large propane-powered households
Best Premium Gas Pick – Rinnai RXP199iN Smart Sense Tankless Water Heater
If you want tankless water heaters with leak detection, the Rinnai RXP199iN offers strong whole-house performance and smart recirculation, though the supplied specifications do not list a built-in leak-detection system. Its condensing design delivers up to 11.1 GPM, supports natural gas or propane, and can be installed indoors or outdoors with the required outdoor vent cap.
Best For: Large households seeking high-flow gas heating with built-in recirculation.
Pros:
- Up to 11.1 GPM and 199,000 BTU output for multiple fixtures.
- Supports natural gas or propane and indoor or outdoor installation.
- Built-in Smart-Circ recirculation pump helps reduce hot-water wait times.
- UEF .98 efficiency and a Quick Flush feature simplify operation and maintenance.
Cons:
- Wi-Fi control requires the separately sold Control-R module.
- Professional installation is recommended, and outdoor installation requires an RX-OVC vent cap.
- No leak-detection feature is identified in the supplied product information.
The RXP199iN is a capable high-output choice for buyers prioritizing flow rate, fuel flexibility, and recirculation. Pair it with a separate leak-detection system if that protection is essential.
Best Dedicated Leak Protection – Floodmaster Water Heater Leak Detection System
For shoppers comparing tankless water heaters with leak detection, the Floodmaster RS-094-3/4 is a dedicated add-on rather than a water heater. It uses a contact sensor, audible alarm, and automatic shutoff valve to help protect a water heater or tank installation from leaks.
Best For: Adding leak detection and automatic water shutoff to a compatible 3/4-inch water-heater connection.
Pros:
- Combines leak sensing, an audible alarm, and automatic shutoff.
- Includes an 8-foot sensor cord and 12-foot power cord.
- Uses a 3/4-inch NPT connection and supports up to 80 psi.
- High-impact ABS construction with a brass valve.
Cons:
- It is a protection system, not a tankless water heater.
- Only one sensor is included.
- Compatibility should be confirmed for the intended plumbing setup.
This is the most directly relevant product for the leak-detection part of the buying decision. It can complement a compatible tankless heater, but it does not provide heating capacity or hot-water control.
Best Built-In Leak Detection – Rheem RTG 9.5 GPM LP Tankless Water Heater
Among these tankless water heaters with leak detection, the Rheem RTG Series stands out because its listed features include Rheem LeakGuard leak detection and prevention. This indoor liquid-propane model supplies 9.5 GPM at a 35°F temperature rise and includes Wi-Fi connectivity for whole-home use.
Best For: Families needing indoor propane heating for several simultaneous showers with integrated leak protection.
Pros:
- Built-in LeakGuard leak detection and prevention system.
- 9.5 GPM flow and 199,900 BTU output for approximately 3–4 simultaneous showers.
- EcoNet Wi-Fi technology and digital temperature adjustment.
- Includes freeze protection and flame-failure protection.
Cons:
- Designed for indoor installation and liquid propane.
- Non-condensing efficiency is listed at 0.82 UEF.
- Professional installation is required.
The Rheem is the clearest all-in-one match for this roundup’s keyword because leak protection is built into the heater’s listed feature set. Its 9.5 GPM capacity makes it a practical choice for many-bathroom homes, provided the indoor propane requirements fit your installation.
Best Electric Option – Stiebel Eltron Tempra 15 Plus
The Stiebel Eltron Tempra 15 Plus is an electric tankless heater with no venting requirement and a compact wall-mounted design. It does not list a built-in leak-detection system, but its included seven-year leakage warranty may appeal to buyers evaluating tankless water heaters with leak detection and related protection features.
Best For: Homes with adequate electrical service seeking compact, whole-house electric water heating.
Pros:
- Advanced Flow Control helps maintain temperature when demand exceeds capacity.
- Compact 16.63-by-14.5-inch design requires no venting.
- Electronic modulation, digital display, and preset temperature controls.
- Includes a seven-year leakage warranty and three-year parts warranty.
Cons:
- Requires 240V hardwiring, a minimum recommended 100A service, and a 60A draw.
- Its 14.4 kW output may be less suitable for very high simultaneous demand than larger gas models.
- No leak-detection alarm or automatic shutoff is listed.
The Tempra 15 Plus is a strong space-saving alternative when gas installation is undesirable or unavailable. Confirm the home’s electrical capacity first, and add a separate leak-detection and shutoff device if active monitoring is required.
High-Capacity LP Pick – Rheem RTG Series 9.5 GPM
For shoppers comparing tankless water heaters with leak detection, this outdoor Rheem propane model stands out for whole-home capacity and built-in safety features. Its 9.5 GPM flow rate and 199,900 BTU output are designed for demanding households, while Wi-Fi connectivity adds convenient monitoring and control.
Best For: Large families and multi-bathroom homes with outdoor LP installation space.
Pros:
- 9.5 GPM output can support multiple simultaneous showers.
- Outdoor installation eliminates the need for venting.
- Includes freeze protection and flame-failure protection.
- Offers Wi-Fi connectivity, a 15-year heat-exchanger warranty, and a 5-year parts warranty.
Cons:
- Requires liquid propane and professional installation.
- Its outdoor-only design may not suit homes without an appropriate installation location.
- The supplied features do not specifically identify an integrated leak-detection function.
This is a strong capacity-focused option when propane availability and outdoor installation are priorities. Buyers specifically seeking leak detection should confirm the exact safety and monitoring features with the manufacturer before purchasing.
Compact Electric Choice – Rheem RTEX-24 24kW
Among tankless water heaters with leak detection, the Rheem RTEX-24 is a compact electric option with a stated 5-year leak warranty. It heats water only when a tap is open, requires no venting, and provides digital temperature adjustment for whole-home applications when the electrical service is properly sized.
Best For: Homes with adequate 240V electrical capacity that want a space-saving, whole-home electric heater.
Pros:
- Provides up to 5.9 GPM for multiple fixtures.
- Compact design is 90% smaller than traditional tank water heaters.
- Requires no gas venting.
- Digital controls adjust temperature in 1-degree increments from 80°F to 140°F.
Cons:
- Requires three 40-amp double-pole breakers, three sets of #8 AWG copper conductors, and a recommended minimum 200-amp service panel.
- Professional installation and electrical-system verification are important.
- The supplied notes mention a leak warranty but do not confirm active leak detection or an alarm.
The RTEX-24 makes the most sense where electrical infrastructure can handle its demanding requirements. Its documented leak warranty may appeal to cautious buyers, but it should not be treated as proof of built-in leak detection without further confirmation.
Compact Propane Pick – Rinnai V53DeP 5.3 GPM
For buyers researching tankless water heaters with leak detection, the outdoor Rinnai V53DeP offers propane-powered on-demand heating in a compact package. Its enhanced scale-detection features may support maintenance awareness, while the 5.3 GPM flow rate suits moderate household demand.
Best For: Smaller households needing an outdoor propane heater with space-saving installation.
Pros:
- 5.3 GPM flow rate supplies hot water to multiple appliances.
- Compact outdoor design fits tighter installation spaces.
- Enhanced scale detection helps support maintenance planning.
- Offers Wi-Fi capability and a 10-year heat-exchanger warranty.
Cons:
- Professional installation is recommended.
- Lower flow capacity than the 9.5 GPM Rheem propane model, making it less suited to peak simultaneous demand.
- The supplied notes describe scale detection, not dedicated leak detection.
This Rinnai is a practical fit when compact outdoor propane installation matters more than maximum flow. Because scale detection and leak detection address different issues, confirm whether a separate leak-monitoring accessory or system is needed.
Best Whole-Home Gas Pick – Rheem RTG 9.5 GPM Natural Gas
For shoppers comparing tankless water heaters with leak detection, the Rheem RTG Series combines high-demand natural-gas performance with Wi-Fi connectivity and LeakGuard leak detection and prevention. Its 9.5 GPM capacity and 199,900 BTU output are designed for larger households, while the indoor direct-vent design saves floor space.
Best For: Large families and multi-bathroom homes that may run three to four water points simultaneously.
Pros:
- 9.5 GPM flow rate and 199,900 BTU output support substantial whole-home demand.
- Built-in Wi-Fi and LeakGuard leak detection and prevention add remote monitoring and protection.
- Non-condensing design includes freeze and flame-failure protection.
- Offers a 15-year heat-exchanger warranty and five-year parts warranty.
Cons:
- Requires professional installation and an indoor direct-vent setup.
- Natural-gas operation may not suit homes without an appropriate gas supply.
This is a strong choice when whole-home capacity and integrated leak protection matter more than the simplicity of electric installation. Confirm venting, gas, and professional-installation requirements before buying.
Best Heavy-Duty Pick – Westinghouse 14kW Electric
The Westinghouse 14kW is an electric option for shoppers seeking tankless water heaters with leak detection in a compact, connected package. It provides 98% thermal efficiency, Wi-Fi and voice controls, and four-layer protection that includes leakage protection, making it suited to smaller residential hot-water demands.
Best For: Apartments, cabins, smaller homes, and other spaces with suitable 240V electrical service.
Pros:
- Compact wall-mountable design takes up no floor space.
- Wi-Fi, Alexa, Google Home compatibility, and temperature memory simplify control.
- Four-layer protection includes leakage, overheat, dry-fire, and over-voltage safeguards.
- 98% thermal efficiency and a 3-second heating claim support responsive operation.
Cons:
- Requires a dedicated 60A double-pole breaker and 6 AWG wire at 240V.
- Its listed 3.4 GPM output is intended for about two simultaneous water points under specified conditions.
- Inlet filter and rotor cleaning is recommended every six months.
This model makes sense where electrical capacity is available and installation space is limited. Its protection features include leakage protection, but the product notes do not identify a separate LeakGuard-style prevention system.
Best High-Efficiency Propane Pick – Rheem RTGH 9.5 GPM LP
The Rheem RTGH Series is a high-capacity propane choice among tankless water heaters with leak detection. It pairs 9.5 GPM output and 199,900 BTUs with condensing technology, 0.93 UEF efficiency, built-in EcoNet Wi-Fi, and LeakGuard alerts and prevention for demanding whole-home installations.
Best For: Large households using liquid propane and needing simultaneous hot water across multiple bathrooms.
Pros:
- 9.5 GPM flow and 199,900 BTU output are designed for three to four simultaneous showers.
- Condensing technology and a 0.93 UEF rating support efficient operation.
- EcoNet Wi-Fi and LeakGuard provide smartphone monitoring, alerts, and leak prevention.
- Supports PVC vent runs up to 150 feet with 3-inch piping, according to the supplied notes.
Cons:
- Requires professional indoor installation with direct venting.
- Liquid-propane operation is not suitable for homes configured only for natural gas.
- Condensing installation may involve additional venting and condensate considerations.
For propane-powered homes, this model offers an appealing combination of peak-demand capacity, efficiency, and connected leak protection. Verify fuel compatibility, venting layout, and installation requirements with a qualified professional.
How We Picked the Best Tankless Water Heaters with Leak Detection
We selected products across the main installation categories: natural gas, liquid propane, electric, indoor, outdoor, and smart-connected systems. We also included a dedicated leak-detection device because leak protection is often an add-on rather than a built-in feature. Our comparisons focus on flow capacity, energy input, installation flexibility, efficiency, controls, warranty considerations, and suitability for different home sizes.
Before purchasing, verify that the unit’s fuel type, voltage, gas supply, venting method, pipe size, and electrical requirements match your home. Professional installation is especially important for gas-fired models.
Quick Comparison
| Best For | Recommended Type | What to Prioritize |
|---|---|---|
| Large households | High-output gas or propane | About 9.5 GPM, adequate gas supply, reliable venting |
| Smaller homes or apartments | Electric tankless | Available amperage, voltage, and simultaneous demand |
| Remote or exposed installation | Outdoor gas or propane | Freeze protection, weather rating, and fuel access |
| Leak-conscious homeowners | Heater plus leak detector | Automatic shutoff, alarm, sensors, and monitoring |
| Connected homes | Smart-enabled heater or accessory | App support, alerts, and dependable Wi-Fi coverage |
Key Buying Factors for Tankless Water Heaters with Leak Detection
Fuel and Installation Requirements
Gas and propane units usually provide higher flow rates for multiple simultaneous showers, but they require combustion air, venting, fuel capacity, and professional setup. Electric models are often simpler to vent because they have no combustion exhaust, yet high-output versions may require multiple dedicated circuits and substantial service-panel capacity.
Flow Rate and Temperature Rise
Look at gallons per minute rather than relying only on the heater’s maximum rating. A unit’s practical output falls as incoming water gets colder or the desired temperature rises. Estimate how many fixtures may run at once, then leave some capacity for seasonal changes.
Leak Detection and Automatic Shutoff
A leak sensor can alert you to water near the heater, while an automatic shutoff system can stop the supply before a small leak becomes major damage. Check whether sensors are included, whether the device connects to a valve, how alerts are delivered, and whether installation requires compatible plumbing or a hub.
Efficiency and Controls
Compare efficiency ratings, modulation, recirculation compatibility, temperature controls, and available diagnostics. Wi-Fi features are useful when they provide meaningful alerts and usage information, not simply remote temperature adjustment.
Who Should Buy Which Tankless Water Heaters with Leak Detection?
Choose a high-output indoor gas or propane model if your household regularly runs multiple hot-water fixtures at once and you already have suitable fuel and venting infrastructure. An outdoor gas or propane unit can simplify placement when indoor venting is difficult, provided the climate and freeze-protection requirements are appropriate.
Electric models are a practical fit for smaller households, additions, and homes without gas service, but confirm electrical capacity before ordering. A dedicated leak-detection system is worth considering with any tankless heater—particularly in finished basements, utility closets, rental properties, or homes that are frequently unoccupied. For the strongest protection, pair compatible sensing with automatic water shutoff and phone alerts.