10 Best Tankless Water Heaters of 2026 for Efficient, On-Demand Hot Water

Tankless water heaters deliver hot water on demand while taking up less space than conventional storage tanks. The right model depends on fuel type, flow rate, electrical capacity, installation requirements, and the number of fixtures you use at once.

This roundup compares 10 options ranging from high-output whole-home gas systems to compact electric and portable units, so you can narrow your choice by household size, location, and budget.

Best 10 Tankless Water Heaters Picks for 2026

Best High-Capacity Gas Pick – Rinnai RX199iN

For households that need substantial simultaneous hot-water capacity, the Rinnai RX199iN is a powerful tankless water heater with up to 11.1 GPM and a 199,000-BTU output. Its condensing design, Smart Sense gas controls, and indoor/outdoor installation flexibility make it a versatile option, though professional installation is recommended.

Best For: Larger households needing hot water for multiple fixtures at once.

Pros:

• Provides up to 11.1 GPM, supporting as many as seven fixtures at once.
• Supports natural gas or propane through the Smart Sense gas control system.
• Can be installed indoors or outdoors with the Versa Vent system.
• Offers a .98 UEF and a Quick Flush feature for easier maintenance.

Cons:

• Outdoor installation requires the separate RX-OVC vent cap.
• Professional installation is recommended.
• Wi-Fi control requires an optional Controlr module.

The RX199iN is a strong choice when maximum flow and fuel flexibility matter most. Confirm local gas, venting, and installation requirements before buying, and register the product within 90 days to preserve the stated labor warranty terms.

Best Whole-Home Electric Pick – Rheem RTEX-24

The Rheem RTEX-24 is a whole-home electric tankless water heater rated for up to 5.9 GPM. It heats water on demand without venting and uses digital controls with one-degree temperature adjustments, but its substantial electrical requirements should be verified before installation.

Best For: Homes with suitable electrical service that want whole-home electric water heating without gas venting.

Pros:

• Delivers up to 5.9 GPM for multiple fixtures.
• Does not require venting, simplifying installation compared with gas models.
• Digital thermostatic controls adjust from 80°F to 140°F in one-degree increments.
• Compact design is listed as 90% smaller than traditional tank water heaters.

Cons:

• Requires 240V single-phase power, three 40-amp double-pole breakers, and three sets of #8 AWG copper conductors.
• A recommended minimum 200-amp household service panel may limit compatibility.
• Professional electrical installation may be necessary.

With a stated 99.8% energy efficiency rating and no venting requirement, the RTEX-24 can be appealing where the electrical infrastructure is already adequate. Confirm the panel capacity and wiring requirements before choosing this model.

Best Mid-Range Gas Pick – Rinnai RX160iN

The Rinnai RX160iN balances strong household capacity with a slightly smaller output than the brand’s higher-capacity model. This condensing tankless water heater provides up to 9 GPM, supports natural gas or propane, and allows indoor or outdoor installation when configured with the required venting components.

Best For: Medium-to-large households seeking flexible gas-fuel and installation options.

Pros:

• Provides up to 9 GPM, supporting as many as six fixtures at once.
• Works with natural gas or propane using Smart Sense controls.
• Supports indoor or outdoor installation with Versa Vent.
• Includes Quick Flush functionality and a .97 UEF.

Cons:

• Outdoor installation requires the RX-OVC vent cap.
• Professional installation is recommended by the manufacturer.
• Wi-Fi connectivity requires an optional module.

The RX160iN is a practical middle ground for buyers who need more capacity than a smaller unit but do not require the RX199iN’s maximum flow. Check groundwater temperature, fuel availability, venting, and local installation requirements before purchase.

Best Compact Electric Pick – Rheem RTEX-13

The Rheem RTEX-13 is a compact 13kW electric tankless water heater designed for applications requiring up to 3.17 GPM, according to the supplied product notes. It features external digital temperature control, self-modulating power control, and field-serviceable copper heating elements.

Best For: Smaller homes, point-of-use applications, or installations with moderate hot-water demand.

Pros:

• Compact electric design with external digital temperature adjustment.
• Provides one-degree temperature control through the LED display.
• Uses self-modulating power control and two field-serviceable copper heating elements.
• Includes 1/2-inch NPT adapters and a 1.5-GPM water-saving shower head.

Cons:

• The supplied notes list up to 3.17 GPM for the 13kW model, limiting simultaneous demand.
• Requires 240V power and draws 54 amps.
• May be undersized for larger households or multiple high-flow fixtures.

The RTEX-13 makes the most sense when space is limited and hot-water demand is moderate. Its electrical load and expected flow should be checked carefully, especially if it will serve more than one fixture at a time.

Best for Easy Setup – EcoSmart ECO 8

The EcoSmart ECO 8 is a compact electric option for shoppers comparing tankless water heaters for a single point of use or a smaller hot-water demand. Its 8-kW output, 2 GPM flow rate, wall-mount design, and 99.8% stated efficiency make it easy to evaluate where space and electrical operation matter most.

Best For: Compact applications needing an electric, wall-mounted tankless water heater with an LED display.

Pros:

• Compact 8-inch-wide, 4-inch-deep design
• 99.8% stated efficiency
• LED display and stainless-steel construction
• Lifetime warranty on the electronics, exchanger, and element

Cons:

• Limited to an 8-kW output and 2 GPM flow rate
• Requires a 240-volt electrical connection
• May not suit higher simultaneous hot-water demand

Choose this model when compact size and electric operation are priorities. Its modest flow rate makes it a more focused choice than a whole-home unit designed for multiple simultaneous showers.

Best Whole-Home Gas Pick – Rheem RTG 7.0 GPM

The Rheem RTG Series is a whole-home natural-gas option among tankless water heaters, offering 7.0 GPM at a 35°F temperature rise and 160,000 BTU/hr output. Its indoor wall-mount format, digital controls, safety features, and stated capacity for two to three simultaneous showers make it suited to larger residential demand.

Best For: Large families and multi-bathroom homes using natural gas and needing hot water at multiple points simultaneously.

Pros:

• 7.0 GPM flow rate with 160,000 BTU/hr output
• Designed for two to three simultaneous showers
• Digital temperature control with ±1°F adjustments
• Includes freeze, flame-failure, and LeakGuard protection features

Cons:

• Requires natural gas and indoor direct-vent installation
• Larger and heavier than compact electric models
• Non-condensing design has a stated 0.82 UEF

This Rheem is the strongest fit here for high-demand whole-home use when a suitable natural-gas and venting setup is available. Its warranty coverage includes 15 years for the heat exchanger, five years for parts, and one year for labor.

Best Mid-Range Electric Pick – Rheem RTEX-18

The Rheem RTEX-18 is a higher-output electric choice for shoppers comparing tankless water heaters for whole-home use. It provides 18 kW of power, up to 4.4 GPM flow, 99.8% stated efficiency, and self-modulation that adjusts power according to hot-water demand.

Best For: Electric whole-home applications needing more capacity than a compact 8-kW unit.

Pros:

• 18-kW output with flow rates up to 4.4 GPM
• Self-modulating power adjusts to demand
• External digital thermostat with LED display and ±1°F accuracy
• Field-serviceable copper immersion heating elements

Cons:

• Requires a 240-volt AC power connection
• Higher electrical output may require appropriate home wiring capacity
• Maximum listed flow is below the Rheem 7.0 GPM gas model

The RTEX-18 balances electric installation with substantially more output than the ECO 8. It is a practical match for buyers who want digital control and demand-based heating, provided their electrical system can support the unit.

Best Portable Pick – CAMPLUX 5L Outdoor Propane Heater

For camping, RV travel, and off-grid use, this portable tankless water heater provides hot water without relying on household electricity. Its 1.32 GPM output, low-pressure startup, and included shower hardware make it a practical choice for outdoor washing and bathing.

Best For: Campers, RV owners, remote cabins, and outdoor cleanup.

Pros:

• Lightweight 10-pound design with a folding handle for easier transport.
• Starts at 3.0 PSI and can work with a small 12V pump or gravity-fed water source.
• Includes a shower head, hose, gas regulator, and hardware for a straightforward setup.
• CSA certified with multiple protections, including overheat and flame-failure protection.

Cons:

• Its 1.32 GPM flow rate is intended for a single outdoor shower or similar task.
• Requires propane and two D-size batteries, so it is not a plug-in solution.
• Maximum temperature is listed at 114°F.

The CAMPLUX AY132 is a useful portable option when compact size and off-grid operation matter more than whole-home capacity. It is especially suited to outdoor showers, pet washing, and camp cleanup.

Best Multi-Fixture Electric Pick – Rheem 11kW Tankless Heater

This Rheem model is a compact electric tankless water heater designed for properly sized multi-fixture applications. It delivers up to 2.68 GPM, uses digital one-degree temperature controls, and requires no venting, but its electrical requirements should be confirmed before installation.

Best For: Homes needing compact, on-demand electric hot water for multiple fixtures.

Pros:

• Provides up to 2.68 GPM for multi-fixture applications.
• Digital controls adjust temperature from 80°F to 140°F in one-degree increments.
• Compact design is listed as 90% smaller than traditional tank water heaters.
• 99.8% efficiency and no venting requirement simplify the comparison with gas systems.

Cons:

• Requires 240V single-phase power, a 50-amp double-pole breaker, and #8 AWG copper conductors.
• The manufacturer recommends at least a 100-amp household service panel.
• Professional installation and correct sizing are important for the stated performance.

The RTEX-11 is a strong fit for buyers who want electric, wall-mounted hot water without a storage tank or venting. Verify the available electrical service before choosing it for a home installation.

Best Point-of-Use Pick – CAMPLUX 4.5kW Under-Sink Heater

For a single sink or other point-of-use location, this compact electric tankless water heater delivers hot water on demand from a 120V circuit. Its self-modulating design, LED temperature display, and small wall-mounted profile suit kitchens, wet bars, boats, and other space-limited installations.

Best For: One-sink applications where compact size and localized hot water are priorities.

Pros:

• Compact 10.95-by-2.52-by-7.4-inch design fits tight spaces.
• Activates at a low 0.26 GPM flow and provides a listed 50°F temperature rise at 1.0 GPM.
• Self-modulating power adjusts to flow rate and temperature settings.
• Touch controls and an LED display make temperature adjustments convenient.

Cons:

• Designed for one sink rather than whole-home or multi-fixture demand.
• Must be hardwired and requires a 40A circuit breaker with 10 AWG wire.
• It uses a 1/2-inch NPT water connection and does not use a standard plug.

The CAMPLUX TE05N4 makes sense when you need localized hot water without adding a storage tank. Its installation requirements are substantial for a small unit, so confirm the circuit and plumbing setup first.

How We Picked the Best Tankless Water Heaters

We selected these Tankless Water Heaters to cover the most common installation scenarios: whole-home gas systems, high-capacity electric models, smaller point-of-use units, and portable propane or electric heaters. We focused on stated flow rate, heating capacity, fuel type, installation format, intended use, and the practical demands of replacing or adding a water heater.

Because performance varies with incoming water temperature, flow rate, and available utilities, product specifications should be treated as starting points rather than guaranteed output. Always confirm local code requirements and installation instructions before purchasing.

Quick Comparison

Best for	Recommended type	What to prioritize
Large households	High-output condensing gas	High GPM, gas supply, venting, and simultaneous-use capacity
Moderate electric demand	18kW–24kW electric	Electrical panel capacity, wiring, breakers, and incoming-water temperature
Single sink or remote fixture	Point-of-use electric	Compact size, low flow, simple plumbing, and outlet access
Camping or off-grid use	Portable propane or electric	Water source, fuel or power availability, safety features, and portability

Key Buying Factors for Tankless Water Heaters

Fuel Type and Installation

Gas models can provide substantial flow for multiple fixtures, but they may require gas-line upgrades, approved venting, condensate drainage, and professional installation. Electric units generally have simpler exhaust requirements, yet high-output models can require multiple dedicated circuits and a panel capable of handling significant amperage.

Flow Rate and Temperature Rise

Gallons per minute is only part of the equation. A heater must raise incoming water to the desired temperature while serving the required fixtures. Cold climates and winter groundwater can reduce available flow, so choose based on your realistic peak demand rather than the maximum number printed on the box.

Household Demand

List the fixtures you may use simultaneously, such as showers, faucets, a dishwasher, or a washing machine. A compact point-of-use model may suit one sink but will not replace a whole-home system. For larger households, prioritize higher output and stable performance at multiple flow rates.

Space, Controls, and Maintenance

Measure the installation area and check water, gas, electrical, and vent connections before ordering. Digital controls and smart features can simplify monitoring, while scale buildup can reduce performance. In hard-water areas, plan for filtration or periodic descaling according to the manufacturer’s schedule.

Who Should Buy Which Tankless Water Heaters?

• Choose a high-output condensing gas model for a large home, multiple simultaneous showers, or strong whole-home demand when gas service and proper venting are available.
• Choose a high-capacity electric model when you want on-demand heating without combustion venting and your electrical system can support the required load.
• Choose a mid-range electric unit for apartments, smaller households, or moderate demand after confirming voltage, amperage, and expected temperature rise.
• Choose a compact point-of-use heater for a distant sink, workshop, guest space, or other low-flow application rather than full-home service.
• Choose a portable propane unit for camping, RV use, outdoor washing, or off-grid situations where a standard household installation is impractical.

Before buying, verify fuel compatibility, electrical requirements, connection sizes, local permitting, and whether professional installation is recommended. The best Tankless Water Heaters are the ones that match your home’s available utilities and peak hot-water demand—not simply the model with the highest advertised output.