In today’s world, where energy efficiency and space-saving solutions are paramount, tankless water heaters have surged in popularity. Unlike traditional water heaters that store hot water in bulky tanks, tankless models heat water on demand, providing an endless supply of hot water while significantly reducing energy consumption. This technology not only cuts down on utility bills but also frees up valuable space in your home, making it an excellent choice for modern households.
When shopping for the best tankless water heater on Amazon, you’ll find a vast array of options catering to different needs-whether you want a compact unit for a small apartment or a powerful whole-house system. The key is to balance factors such as power source (electric or gas), flow rate, installation type, and budget. Choosing the right model can mean reliable hot water for years with minimal maintenance and maximum savings.
In this post, I’ll guide you through the 7 best tankless water heaters available on Amazon in 2025, highlighting their features, pros, and ideal use cases. Whether you want to upgrade your current system or install a new one, this comprehensive guide will help you make an informed, confident choice.
How to Choose the Best Tankless Water Heater
As someone who has researched and tested numerous water heaters, I know that picking the right tankless water heater goes beyond brand names and price tags. Here’s what I focus on to ensure you get the best value and performance:
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Power Source: Decide between electric and gas models. Electric tankless heaters are easier to install and ideal for smaller homes or point-of-use applications, while gas units (natural gas or propane) provide higher flow rates suitable for whole-house use.
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Flow Rate (GPM): Calculate your household’s peak hot water demand by adding up the flow rates of showers, faucets, and appliances used simultaneously. Choose a model that can deliver at least that many gallons per minute (GPM) at your desired temperature rise.
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Temperature Rise: This is the difference between incoming water temperature and the desired output temperature. Colder climates require heaters with higher capacity to maintain hot water temperature.
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Installation Location: Some models are designed for indoor use, others for outdoor installation. Venting requirements differ accordingly, impacting installation cost and complexity.
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Energy Efficiency: Look for units with high energy factor (EF) ratings and features like self-modulating technology that adjusts power consumption based on demand.
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Warranty and Support: Reliable brands offer solid warranties on heat exchangers and parts, ensuring peace of mind.
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Size and Space: Tankless heaters are compact, but you still need to ensure you have adequate space and proper electrical or gas hookups.
Now, let’s dive into the top 7 tankless water heaters you can confidently buy on Amazon today.
7 Best Tankless Water Heater (Reviews)
01. Rheem Performance Tankless Electric Water Heater
The Rheem Performance Tankless Electric Water Heater stands out as a versatile, energy-efficient choice for midsize to large homes. It supports up to five showers running simultaneously, making it perfect for families with high hot water demand. This model features self-modulating technology that automatically adjusts energy use based on your household’s needs, optimizing efficiency and reducing utility bills. The digital display allows precise temperature control in one-degree increments, enhancing user convenience.
Installation is straightforward with an easy flex-hose option, and since it’s electric, no venting is required, simplifying setup and maintenance. Rheem backs this model with a five-year heat exchanger warranty and a one-year parts warranty, underscoring its reliability. Whether you’re upgrading an existing system or installing new, this tankless water heater offers excellent performance and value for continuous hot water supply.
02. Stiebel Eltron Tempra Plus 24 Electric Tankless Water Heater
Known for its German engineering excellence, the Stiebel Eltron Tempra Plus 24 is a top-tier electric tankless water heater that delivers precise temperature regulation and quiet operation. Featuring advanced flow control technology, it maintains consistent water temperature even when multiple fixtures are used simultaneously. This model is ideal for whole-house applications in moderate climates.
Its compact design fits easily in tight spaces, and the digital controls allow you to adjust settings with ease. The Tempra Plus 24 is highly energy-efficient, helping homeowners save on electricity bills without compromising comfort. With a reputation for durability and backed by a strong warranty, this unit is a smart investment for those seeking reliable, on-demand hot water with minimal fuss.
03. EcoSmart ECO 27 Electric Tankless Water Heater
The EcoSmart ECO 27 is a popular choice for energy-conscious consumers looking for a compact yet powerful electric tankless water heater. It boasts a self-modulating technology that adjusts energy consumption to the exact hot water demand, improving efficiency and lowering operating costs. This model can handle multiple fixtures at once, making it suitable for medium-sized homes.
Installation is user-friendly, and its sleek design fits well in small spaces. The ECO 27’s durable construction and digital temperature control provide precise and reliable hot water delivery. It’s also one of the most affordable high-capacity electric tankless heaters on Amazon, earning excellent customer reviews for performance and value.
04. Rinnai RU199iN Natural Gas Tankless Water Heater
For those preferring gas-powered solutions, the Rinnai RU199iN is a leading natural gas tankless water heater designed for whole-house use. It delivers an impressive flow rate of up to 11 GPM, enough to supply multiple bathrooms and appliances simultaneously. This model features advanced condensing technology that maximizes energy efficiency and reduces emissions.
The RU199iN is Wi-Fi enabled, allowing remote temperature control and monitoring via a smartphone app, adding convenience and smart home integration. Its durable stainless steel heat exchanger ensures longevity, and Rinnai’s reputation for quality and support makes this an authoritative choice for homeowners seeking a high-performance gas tankless water heater.
05. Rheem RTEX-13 Electric Tankless Water Heater
The Rheem RTEX-13 is a compact, affordable electric tankless water heater perfect for point-of-use applications such as single bathrooms, kitchens, or small apartments. It offers easy installation and adjustable thermostat settings, allowing temperature control up to 140°F. Despite its small size, it provides reliable hot water on demand with minimal energy waste.
This model is ideal for users who want to supplement their main water heater or install hot water closer to the fixture to reduce wait times. Its durable copper immersion heating elements and digital controls make it a dependable choice for smaller households or limited spaces.
06. Camplux 5L Outdoor Propane Tankless Water Heater
The Camplux 5L is a propane-powered outdoor tankless water heater designed for versatility and portability. It’s perfect for outdoor showers, camping, or remote locations without electrical access. The unit heats water instantly with a flow rate suitable for one or two fixtures.
Its compact design and easy installation make it a favorite among RV owners and outdoor enthusiasts. Safety features include flame failure and overheating protection. The Camplux 5L offers a practical, energy-efficient solution for on-demand hot water wherever you need it.
07. Takagi T-KJr2-IN-NG Condensing Natural Gas Tankless Water Heater
Takagi’s T-KJr2-IN-NG is a high-end, condensing natural gas tankless water heater ideal for homeowners seeking premium efficiency and performance. It features a stainless steel heat exchanger and advanced combustion technology that delivers hot water efficiently while minimizing fuel consumption.
This model supports whole-house applications with a flow rate sufficient for multiple simultaneous uses. It’s designed for indoor installation with low NOx emissions, making it environmentally friendly. Takagi’s strong warranty and customer support reinforce its status as a trusted, authoritative brand in the tankless water heater market.
Conclusion
Choosing the best tankless water heater depends on your household’s size, hot water demand, power source preference, and installation constraints. Whether you prioritize energy efficiency, smart features, or compact design, the models listed here represent the top-performing, most reliable options available on Amazon in 2025. From the versatile Rheem Performance Electric to the high-capacity Rinnai RU199iN gas heater, these units deliver continuous hot water on demand, reduce energy costs, and save space.
