Tankless water heaters many use them, and they have so many benefits. But what are some of the downsides to consider when it comes to tankless water heaters? For starters, tankless units require a lot of maintenance. They need to be pumped annually due to deposits that form from the water. Power is another issue. If the power goes out, then you won't have any hot water like you may with a tank water heater. If the heater is outside, you need to make sure it can withstand the cold temperatures. Most people who live in colder parts of the country would need to store these in a basement or somewhere indoors where the temperature is controlled. Watch Matt Risinger's full video to learn more about tankless water heater cons.