Bidet Toilet Seat Water Heating Systems

Modern electronic bidet seats are equipped with built-in water heaters. The ability for the bidet seat to heat the water is a major benefit since most people prefer warm water to wash themselves. Although a shock of cold water may be effective in waking you up in the morning, it’s not exactly the best way to start your day.

Having a water heater inside your bidet seat is also great because it makes installation a lot easier. All you need is the existing cold water supply behind your toilet, making a separate hot water line unnecessary. Water temperature is adjustable too, as you’ll be able to set the temperature over three to five different settings (depending on model), ranging in temperature between 92 and 105 degrees Fahrenheit.

The “reservoir tank water heater” and “on-demand water heater” are the two types of heating systems you’ll find in bidet toilet seats today. And in doing your bidet seat research, you may have come across these terms to describe how the seat’s heater works. But what are these heating systems really, and what are the benefits of having one over the other?

Let’s start with reservoir tank water heaters first. These types of heaters are similar in concept to the water heater you have at home, which supplies hot water to your whole house. Now – picture a mini water tank inside your bidet seat. It’s basically a small reservoir tank heater, which is where the name “reservoir tank water heater” comes from. Here are the pros and cons of reservoir tank heaters:


- Typically less expensive
- Warm water is always ready; no initial cold splash
- Lower peak wattage around 700 watts


- These bidet seats are typically bulkier (towards the rear of the unit) to accommodate the water tank inside
- After ~30 seconds the water will start to cool, as the warm water depletes
Note: Since most people wash in < 20 seconds, cool water is usually not an issue

On-demand water heaters on the other hand, typically do not have a reservoir tank. Instead, they work with a heating coil which instantly warms the water as the water passes through. Coffee machines are a good example of something that uses heating coil technology. Here are the pros and cons of on-demand water heaters:


- Continuous warm water that doesn't run out
- These bidet seats tend to have a slimmer profile because they don't have a bulky water tank inside


- Typically more expensive
- You may get an initial cold splash (1 - 2 seconds) as the water heats up
- Higher peak wattage around 1400 watts

When you look at the pros and cons, there are arguments on both sides so it would be inaccurate to say one heating system is "better" than the other. Rather, it comes down to how you weigh the pros and cons, and whether certain benefits are more important to you than others.