You can build a plunge pool in an 8-by-8-foot space. Many plunge pools are about 8 to 12 feet wide, 2 to 24 feet long, and 4 to 8 feet deep. While these pools are smaller than your average swimming pool, you may want additional space for a deck or patio to surround the plunge pool.

Yes, pool pumps use a significant amount of electricity, making them one of the biggest energy consumers in a home. A pool pump can use up to three times as much electricity as a refrigerator. Typically, a residential pool pump consumes about 1 kilowatt-hour (kWh) for every hour it runs. Because pumps often need to run for about eight hours a day to properly filter the water, this can add up to an annual consumption of 3,000 to 5,000 kWh, which can cost between $480 and $800 per year based on average electricity rates.

The amount of electricity your pump uses depends on its size, energy efficiency, and daily run time. To lower your energy consumption, you can choose an energy-efficient or variable-speed pump, ensure it is correctly sized for your pool, and run it only for the minimum time required to keep the water clean.

An easy way to know whether your sand filter has enough sand is to check how full the filter is and what the sand looks and feels like. The filter container should be two-thirds to three-quarters full of sand. Look for interior marks indicating the ideal sand level. If you put your hand into the sand, it should flow through your fingers without clumping. The filter pressure gauge is also an easy indicator—the right amount of sand leads to normal pressure, while too much or too little sand can cause high or low pressure.

Your indoor pool can be heated or unheated, but the decision depends on your local climate. In regions with freezing temperatures, heating your pool will keep it warm during the winter, especially if it’s only covered with a greenhouse enclosure. 

If you keep your swimming water warm and toasty, budget between $300 and $5,700 for the cost of installing a pool heater.