Tankless water heaters can deliver hot water without the bulky storage tank, making them useful for bathroom sinks, showers, guest baths, and compact homes. The right model depends on your outlet, available electrical capacity, water flow, and desired temperature rise.
This roundup compares 10 electric options ranging from compact 110V point-of-use heaters to higher-output 240V systems. Use the guide below to match each type with your bathroom layout and hot-water needs.
Best 10 Tankless Water Heaters for Bathrooms Picks for 2026
Best Balanced Bathroom Pick
ThermoMate 14kW Self-Modulating Heater
- Up to 3.4 GPM for 1–2 fixtures
- 86°F–131°F self-modulating control
- Compact, ETL-certified wall-mounted design
Best For: Small bathrooms needing shower-and-sink coverage
Best Higher-Capacity Option
Rheem 18kW Tankless Electric Heater
- Up to 4.4 GPM flow rate
- 18kW self-modulating performance
- External digital control with LED display
Best For: Households needing more bathroom flow capacity
Best Sink-Specific Pick
ThermoMate 3.5kW 120V Compact Heater
- Fits under sinks and inside tight cabinets
- 0.4–0.66 GPM point-of-use flow
- 1-degree temperature adjustment with display
Best For: Single bathroom sinks and point-of-use installations
Best Easy-Control 14kW Pick
14kW Electric Sink and Shower Heater
- Up to 3.3 GPM for sink-and-shower use
- LED readouts for temperature, flow, and kW
- 1°F control with multiple safety features
Best For: Bathrooms needing precise controls and 1–2 fixture coverage
Compact Faucet Heater
- Integrated faucet heats water as it flows
- LED temperature display and rotating spout
- Big under-bend design for sink installation
Best For: Bathroom and utility sinks needing point-of-use hot water
High-Power Under-Sink Pick
ThermoMate 6kW Tankless Heater
- 6kW self-modulating point-of-use heating
- Compact wall-mounted design for tight spaces
- Requires 240V hardwiring and a 30A breaker
Best For: Bathroom sinks with suitable high-voltage electrical service
Best Space-Saving Pick
CAMPLUX 4.5kW Point-of-Use Heater
- Compact wall-mounted design for tight spaces
- On-demand heating with LED touch controls
- Requires hard wiring and a 40A circuit
Best For: Single-sink bathroom installations with limited space
Best User-Friendly Option
3500W Digital Heater With Shower Kit
- LCD touchscreen simplifies temperature checks
- Variable-frequency design can reduce power use
- Supports wall or shelf mounting, including adhesive mounting
Best For: Simple point-of-use bathroom installations
Best Compact Sink Heater
- Compact design for under-sink point-of-use heating
- LCD display and multiple safety protections
- Not intended for showers; vertical installation required
Best For: Bathroom sinks in apartments, RVs, and compact spaces
Best Balanced Bathroom Pick – ThermoMate 14kW Self-Modulating Heater
For bathrooms that need hot water for a shower and sink, this 14kW ThermoMate is one of the more balanced tankless water heaters for bathrooms. Its self-modulating controls, compact wall-mounted design, and stated flow rate of up to 3.4 GPM are suited to one or two fixtures, depending on inlet-water temperature.
Best For: Small homes, apartments, compact bathrooms, and users who want one unit for a shower and bathroom sink.
Pros:
- Provides up to 3.4 GPM and supports 1–2 fixtures depending on inlet temperature.
- Self-modulating temperature control from 86°F to 131°F.
- Compact 3-inch-deep wall-mounted design with ETL certification and multiple safety protections.
Cons:
- Requires a 150-amp main panel, a dedicated 60-amp double-pole breaker, and 6 AWG copper wiring.
- May not support multiple high-flow fixtures simultaneously in colder incoming-water conditions.
This is a practical middle ground for bathroom use, but the substantial electrical requirements should be confirmed before purchase. Its compact size and separation of water and electrical components make it especially appealing where installation space is limited.
Best Higher-Capacity Option – Rheem 18kW Tankless Electric Heater
The Rheem RTEX-18 is a higher-capacity choice among tankless water heaters for bathrooms, with up to 4.4 GPM and 18kW of power. Its external digital thermostat, precise LED display, and self-modulation make it suitable for households that may need more flow than a compact 14kW unit provides.
Best For: Larger households or bathroom setups where higher flow and support for multiple fixtures are priorities.
Pros:
- Up to 4.4 GPM with 18kW of heating power.
- External digital temperature control with stated ±1-degree accuracy.
- Self-modulating operation and field-serviceable copper immersion heating elements.
Cons:
- Its larger 18kW capacity may require more electrical planning than a smaller bathroom-focused unit.
- Installation still requires suitable 240V service and 3/4-inch NPT water connections.
Choose this Rheem when bathroom demand is likely to exceed what a 14kW heater can comfortably handle. The digital controls and serviceable heating elements add convenience, while the required electrical installation should be evaluated by a qualified professional.
Best Sink-Specific Pick – ThermoMate 3.5kW 120V Compact Heater
This compact 3.5kW ThermoMate is designed for a single sink rather than a full bathroom shower. Among tankless water heaters for bathrooms, it stands out for under-sink installation, 120V operation, a 0.4–0.66 GPM flow range, and a temperature display that can be adjusted in 1-degree increments.
Best For: Bathroom sinks, under-cabinet installations, and point-of-use hot water where shower service is not required.
Pros:
- Very compact 7.9 x 6.4 x 2.5-inch design for tight spaces.
- Self-modulating operation adjusts power to inlet flow and temperature.
- Temperature display, 86°F–131°F setting range, and ETL certification.
Cons:
- Limited to a maximum stated flow of 0.66 GPM, so it is not intended for showers.
- Must be hardwired and requires a 32-amp double-pole breaker with minimum 10 AWG wiring.
This is a focused point-of-use solution for a bathroom sink, especially when running new hot-water lines would be inconvenient. Confirm the hardwiring requirements and avoid treating it as a whole-bathroom or shower heater.
Best Easy-Control 14kW Pick – 14kW Electric Sink and Shower Heater
This 14kW electric heater is built for sink-and-shower applications, delivering up to 3.3 GPM with a digital display and 1°F temperature adjustments. It is a strong candidate among tankless water heaters for bathrooms when you want compact installation, instant heating, and coverage for one or two usage points.
Best For: Bathrooms needing shower and sink coverage with precise electronic temperature control.
Pros:
- Up to 3.3 GPM and stated support for 1–2 simultaneous usage points.
- LED display shows inlet/outlet temperature, GPM, and kW, with 1°F control.
- Compact wall-mount design with leakage, overheating, and automatic shut-off protection.
Cons:
- Requires a dedicated 60-amp circuit breaker and 240V electrical service.
- Its maximum 131°F setting and flow capacity may be limiting for higher-demand multi-fixture use.
The clear display and precise controls make this a convenient bathroom option, particularly for users who want to monitor performance while adjusting temperature. Check both the electrical capacity and expected simultaneous flow before installing.
Compact Faucet Heater – 110V Instant Hot Water Faucet
If you need tankless water heaters for bathrooms at a sink, this faucet-style model combines the tap and heating unit in one compact design. It features 110V electric operation, an LED temperature display, and a 360° rotating spout for everyday washing and rinsing.
Best For: Bathroom or utility sinks where a faucet-mounted, point-of-use hot-water solution fits the layout.
Pros:
- Heats water as it flows through the faucet.
- LED display helps monitor outlet temperature.
- 360° rotating spout offers flexible water direction.
- Compact mixed-material construction with a stainless-steel inlet.
Cons:
- Listed maximum temperature is 104°F, which may be limited for some uses.
- Installation requires checking voltage, water connections, and available sink space.
- Only the water-heater faucet is included.
This is a practical choice for basic sink hot water when you want an integrated faucet design. Confirm that the big under-bend shape and 110V setup match your bathroom before purchasing.
High-Power Under-Sink Pick – ThermoMate 6kW Tankless Heater
For shoppers comparing tankless water heaters for bathrooms, the ThermoMate ET060 is a compact point-of-use unit designed for under- or over-sink installation. Its 6kW system provides a listed 1.07 GPM flow rate at a 35°F temperature rise, with adjustable digital temperature control.
Best For: Bathroom sinks with room for a hardwired 240V under-sink or wall-mounted heater.
Pros:
- Self-modulating operation heats water on demand and is rated at 99.8% efficiency.
- Temperature can be adjusted in 1°F increments using the touch control panel.
- Compact 2.52-inch-deep design suits tight cabinet and under-sink spaces.
- Separated heating and water lines are designed to reduce scale, corrosion, and mineral buildup.
Cons:
- Requires 240V hardwiring, a 30A circuit breaker, and at least 10AWG wire.
- Professional electrical installation may be necessary.
- Performance varies with incoming-water temperature and flow demand.
The ThermoMate offers stronger point-of-use capability than basic faucet-style heaters, but its electrical requirements are substantial. Verify the circuit, wiring, and 1/2-inch NPT connections before selecting it for a bathroom.
Easy-Control Bathroom Option – 110V Digital Tankless Water Heater
This 110V electric unit is a flexible option among tankless water heaters for bathrooms, with wall mounting for space savings and both remote and touch controls. Its 3000W system is designed to deliver on-demand sink hot water, with a listed maximum temperature of 131°F.
Best For: Bathroom or kitchen sinks where remote temperature adjustment and a compact wall-mounted design are useful.
Pros:
- Offers remote-control and touch-screen temperature adjustment.
- Compact 4.3-by-14.5-inch body helps preserve floor and cabinet space.
- Includes dry-heating, high-temperature, and electrical-leakage protection features.
- Three-level power adjustment supports more controlled operation.
Cons:
- Installation notes call for a circuit breaker rated above 32A to help prevent tripping.
- Listed maximum temperature is 131°F, not boiling-water temperature.
- Actual hot-water performance depends on flow and incoming-water conditions.
The WHRITE heater is appealing when convenient controls and a slim wall-mounted format matter. Check the electrical requirements and standard 1/2-inch connections carefully, and use it for compatible point-of-use applications rather than assuming whole-home capacity.
Best Space-Saving Pick – CAMPLUX 4.5kW Point-of-Use Heater
For bathrooms with a single sink and limited cabinet or wall space, the CAMPLUX is a compact option among tankless water heaters for bathrooms. Its 120V, 4.5kW design heats water on demand, while the LED display and touch controls make temperature adjustments straightforward.
Best For: A single bathroom sink, wet bar, or other point-of-use installation where compact size matters.
Pros:
- Heats water on demand, with hot water available in about 3 seconds according to the manufacturer.
- Compact 10.95-by-2.52-by-7.4-inch wall-mounted design.
- Self-modulating operation adjusts power based on flow rate and temperature settings.
- Includes an LED digital display, touch controls, dry-combustion protection, and a 2-year limited warranty.
Cons:
- Designed for one sink rather than a shower or multiple fixtures.
- Requires hard wiring, a 40A circuit breaker, and 10AWG wire; it does not use a plug.
- Installation requires compatible 1/2-inch NPT water connections.
This CAMPLUX model makes the most sense when you want to eliminate standby heating for one sink and have the electrical capacity for its hard-wired installation. Confirm the circuit and water-connection requirements before buying.
Best User-Friendly Option – 3500W Digital Heater With Shower Kit
This 3,500W electric unit is aimed at shoppers who want simple controls and flexible placement for a bathroom or kitchen. As one of the tankless water heaters for bathrooms with an LCD touchscreen, self-checking functions, and variable-frequency operation, it focuses on convenience and basic protection features.
Best For: Users who prioritize a readable display, simple temperature adjustment, and installation on a wall or shelf.
Pros:
- High-definition LCD screen and digital controls make the temperature easy to check and adjust.
- Variable-frequency operation adjusts input power as water flow and the preset temperature change.
- Includes over-temperature protection that stops and resumes heating based on the detected temperature.
- IPX4 water resistance and supplied adhesive accessories support installation on smooth tile or glass without drilling.
Cons:
- The supplied notes do not specify the unit’s voltage, flow-rate performance, or maximum temperature.
- Drill-free mounting is described for smooth surfaces, so other installation surfaces may require a different approach.
- Its 2.6-pound product weight and compact construction do not indicate suitability for whole-home demand.
This model is most appealing when ease of operation and flexible mounting are more important than detailed performance specifications. Verify electrical requirements and expected bathroom flow before installation.
Best Compact Sink Heater – 3000W 110V Under-Sink Model
The 3,000W, 110V model is a practical choice for a bathroom sink, especially in an apartment, RV, or other compact setting. It provides on-demand heating, an LCD display, and several protective functions, but the manufacturer specifically says it is not suitable for showers.
Best For: Under-sink or point-of-use bathroom applications with modest flow requirements and a vertical installation location.
Pros:
- Compact wall-mounted design suits bathrooms, kitchens, apartments, RVs, and camping setups.
- Provides on-demand heating without a preheating wait and supports Fahrenheit or Celsius display settings.
- Includes leakage, dry-boil, overheating, inactivity, and IPX4 protection features.
- Uses standard 1/2-inch NPT connections and includes a 24-month warranty.
Cons:
- Not suitable for showers; the manufacturer notes that showers normally require at least 1.8 GPM.
- Must be installed vertically, not horizontally.
- Requires wiring to a switch rated over 32A and appropriate wire with at least a 2.5-square-millimeter cross-sectional area.
For a bathroom sink, this unit offers a compact 110V format and clear status information without storing hot water. Its flow limitation and electrical installation requirements make it important to plan the application carefully.
How We Picked the Best Tankless Water Heaters for Bathrooms
We organized these Tankless Water Heaters for Bathrooms by intended use, electrical requirements, output, controls, installation style, and practical bathroom compatibility. The selection includes under-sink and wall-mounted point-of-use models for handwashing, as well as more powerful 240V units that may be suitable for showers when properly sized.
Because installation conditions vary, product wattage and advertised flow rate should be treated as starting points rather than guarantees. Actual performance depends on incoming water temperature, plumbing flow, wiring, and the temperature setting.
Quick Comparison
| Type | Typical use | Electrical profile | Best for |
|---|---|---|---|
| 110V, 3,000–3,500W | Sink or handwashing | Standard-voltage point of use | Small bathrooms, vanities, and under-sink installation |
| 4.5–6kW | Single sink or light-duty fixture | Higher-output compact electric | Guest baths and remote fixtures |
| 14kW | Sink and some shower applications | 240V circuit typically required | Users needing more continuous flow |
| 18kW | Higher-demand bathroom use | 240V, substantial circuit capacity | Homes prepared for professional installation |
Key Buying Factors for Tankless Water Heaters for Bathrooms
Voltage, Amperage, and Wiring
Check whether the unit uses 110V or 240V power, then confirm amperage, breaker size, wire requirements, and available panel capacity with an electrician. A higher-wattage heater may require dedicated circuits and should not be connected to an unsuitable outlet.
Flow Rate and Temperature Rise
Do not choose by maximum gallons per minute alone. A heater must raise incoming water to your target temperature while maintaining the fixture’s flow. Cold climates and showers generally demand more output than a bathroom sink.
Point-Of-Use Placement
Under-sink and wall-mounted heaters reduce wait time and can save space, but they still need proper plumbing clearance, drainage protection, and accessible controls. Faucet-style models are designed for very specific installations and should be checked for sink compatibility.
Controls and Safety Features
Digital displays, touch controls, remote controls, temperature memory, and overheat protection can improve usability. Look for recognized electrical safety certification, suitable water connections, and manufacturer instructions that match your installation.
Who Should Buy Which Tankless Water Heaters for Bathrooms?
For a bathroom sink or guest bath: Choose a compact 110V or 3,500W point-of-use model when the goal is handwashing rather than showering.
For a dedicated sink with more output: A 4.5kW to 6kW unit can provide a stronger margin while remaining focused on one fixture.
For a shower-capable setup: Consider a 14kW or 18kW 240V model only after confirming water demand and electrical capacity. Professional installation is especially important for these systems.
For a space-constrained remodel: Prioritize compact dimensions, wall-mounting options, accessible temperature controls, and short plumbing runs. Always verify local code requirements before purchase.