Hot water at the kitchen sink is something you only notice when it’s missing or too slow to arrive. Whether you’re washing dishes, rinsing vegetables, or filling a pot for pasta, waiting for warm water is frustrating and wastes both time and water. A tankless water heater is the easiest way to get instant hot water right where you need it — without running a whole-house system for a single sink.
This guide will help you choose the best tankless water heater for your kitchen sink in 2025. We’ll look at the top models, what features to consider, and how to size them for your needs. By the end, you’ll know exactly which unit to install for instant, reliable hot water every time you turn on the tap.
Why Choose a Tankless Water Heater for the Kitchen Sink
- Instant hot water: No more waiting for warm water to travel from a distant heater
- Energy efficiency: Only heats water when you open the tap
- Space saving: Compact, wall-mounted units fit under most sinks
- Reduced water waste: Less time waiting for warm water means fewer gallons down the drain
How Much Power Do You Need?
The average kitchen sink uses about 1.5–2.2 gallons per minute (GPM) of water. To keep up, your tankless unit should match or exceed this flow rate while heating water from the incoming temperature to your desired temperature — typically 110–120°F.
- Warm climates: 2–3 GPM is often enough
- Cold climates: Look for at least 3–4 GPM capacity
- Electric units are common under-sink solutions, while gas units are more for whole-kitchen or multi-fixture use
Top Tankless Water Heaters for Kitchen Sinks in 2025
1. EcoSmart ECO 11 (Electric)
One of the most popular small electric tankless heaters, the Eco 11 delivers up to 2.6 GPM in warmer climates. It’s compact enough to mount under a sink and works perfectly for hand-washing dishes or light kitchen use.
- Best for: Small households and warm climates
- Pros: Affordable, compact, energy-efficient
- Cons: May struggle in cold climates
2. Stiebel Eltron Mini 6-2 (Electric, Point-of-Use)
This German-made under-sink heater is built for single fixtures like kitchen sinks. It provides hot water instantly at 0.65–1.5 GPM depending on flow, making it ideal for kitchens where space is limited.
- Best for: True point-of-use applications
- Pros: Very compact, high build quality, no standby losses
- Cons: Limited flow for very high-demand situations
3. Rheem RTEX-13 (Electric)
A versatile electric unit that delivers up to 3.17 GPM in warmer climates, the RTEX-13 is powerful enough for a kitchen sink and an additional low-flow fixture. It features digital temperature control and durable copper immersion heating elements.
- Best for: Medium to high kitchen use
- Pros: Higher flow capacity, easy temperature adjustments
- Cons: Requires a dedicated 60-amp breaker
4. Bosch Tronic 3000 T (Electric Mini-Tank)
While technically a small tank unit, it functions much like a tankless for point-of-use applications by storing a few gallons right under the sink. This gives you truly instant hot water and is perfect for kitchens far from the main water heater.
- Best for: Kitchens with long pipe runs
- Pros: Zero wait time, simple plug-in installation
- Cons: Not endless hot water — best for light to moderate use
5. Camplux ME25 (Electric Mini-Tank)
Another great under-sink option, the Camplux ME25 offers 2.5 gallons of stored hot water for immediate use. It refills quickly and works well for light kitchen needs without a full tankless system.
- Best for: Occasional kitchen hot water use
- Pros: Affordable, easy install, compact
- Cons: Limited capacity for extended washing
Electric vs. Gas for Kitchen Sinks
Electric point-of-use heaters are the most common for kitchen sinks due to their compact size and easy installation. They plug into a standard outlet or hardwire into your panel. Gas tankless heaters are more powerful but usually overkill for a single sink unless they also serve multiple fixtures nearby.
Installation Tips
- Mount the heater as close to the sink as possible to minimize heat loss
- Check electrical requirements before purchase — some need a dedicated breaker
- For gas units, professional installation is required for safety
- Follow the manufacturer’s clearance and ventilation guidelines
Maintenance for Longevity
- Flush once a year to prevent scale buildup, especially in hard water areas
- Clean inlet filters as recommended
- Inspect for leaks or corrosion annually
Final Thoughts
For most kitchens, a small electric tankless like the EcoSmart ECO 11 or Stiebel Eltron Mini 6-2 will provide instant, efficient hot water. If you need higher flow, the Rheem RTEX-13 is a solid step up. For absolute zero wait time and occasional use, a mini-tank like the Bosch Tronic 3000 T or Camplux ME25 can be a perfect fit.
With the right tankless water heater under your kitchen sink, you’ll save time, energy, and water — and enjoy a much smoother cooking and cleaning routine.