The cost of installing a French drain around your foundation depends on several factors, including the size of your property, the complexity of the installation, and the materials used. On average, you can expect to pay between $20 to $30 per linear foot for a French drain. Keep in mind that this is a rough estimate, and the actual cost may vary depending on your specific needs and location. It's always a good idea to get multiple quotes from reputable contractors to get a more accurate estimate for your project.