Designing A Spa-Pool Combination That Works In Your Backyard
The addition of a spa or jacuzzi to a pool (either existing or planned) means you're going to have a very relaxing backyard. Not only will you have the big pool for exercise and splashing about, but you'll have the warmer, soothing spa where you'll be able to sit and enjoy just being quiet. The spa can be separate from the pool or integrated into the pool, and each configuration affects water usage, access, and temperature.
Do You Need the Two to Be Separate?
Building a separate spa from the pool is recommended in a number of scenarios. One simply has to do with room; if your yard is crowded and there's no room next to the pool (and the pool isn't big enough to allow closing off a corner of it for a new spa), then you have to place the spa where you can find space. Another reason is that cool water from the main pool can splash into the spa, cooling the warm water (and the environment a lot less calm for spa users if people are splashing water at them). To keep the water temperatures stable, keep the two structures separate.
Overflowing and Water Conservation
Water conservation can be an issue because simple movement can make water surge over the edge of the spa. In a spa that's integrated into a pool, the dividing walls are generally a little lower than the walls at the edge of the pool, so water that surges over the edge will go into the regular pool instead of being wasted as it's splashed onto concrete. If you're worried about water conservation, integrating the spa into your pool design could be a good idea.
However, don't discount separate spas just yet. Many designs have a hidden channel near the base that captures overflowing water and recycles it back into the spa.
Access to Both the Spa and Pool
Spas that are integrated into a pool tend to combine their inner walls with entry points, so people in the pool can easily get into the spa and vice versa. This allows them to avoid the freezing feeling they'd get by getting out of the water in one structure and walking over to the other structure. If that's important to you, you'll want an integrated pool/spa combination.
Keep in mind that "separate" and "integrated" pools and spas each cover a range of designs. You may think you want integrated pools and spas and find a separate spa design that suddenly seems a lot better. Look at catalogs and go to showrooms provided by spa services to see what these would look like.