The increase in property value with the addition of a pool and spa can vary depending on several factors, such as the local real estate market, the size and features of the pool, and the overall condition and maintenance of the installation. On average, homeowners can expect to see an increase in property value of anywhere from 7% to 15%, depending on these factors. However, it is important to note that a pool and spa installation may not be a wise investment in areas where they are not commonly sought after or in homes with limited outdoor space.