A common question among women planning to use a birth pool in labor is how to heat enough water to fill the pool reasonably quickly, and then maintain the water temperature once the pool is full. Most of us here in North America have 30-50 gallon tank water heaters, rather than the tankless gas heaters that much of Europe uses, so we run out of hot water before the pool is full. This is especially challenging if you're using an inflatable pool, rather than one that comes with a built-in heater.
Rather than boiling pots of water on the stove and then hauling them to the birth pool, I have come up with another solution that is portable, fast, and relatively inexpensive. You will need a 5-gallon bucket (plastic or metal), an electric outlet (preferably close to your birth pool), and a bucket heater (the kind used to heat water for livestock tanks). You can find these at a vet/livestock supply store.
These heaters are quick and powerful; they will bring the water to a boil if left in the bucket long enough. This definitely beats boiling water on the stove in relatively small pots and then hauling it to the birth room. Instead, you just put your bucket & bucket heater right near the birth pool, plug it in, and you're good to go!