Question Details:What could we do to minimize the risk?
The property owner would absolutely be liable for many injuries caused by a pool on his/her property.
To minimize risk, if you want to go forward with this, do as much of the following as possible--definitely do items 1, 3, and 6:
1) Make sure you have the right type and amount of insurnace.
2) Have the tenant also provide insurance, naming you as an additional insured.
3) Have the tenant put up a high, locking fence around the pool.
4) Post that no one may swim without the tenant (or property owner) being present.
5) Do NOT allow the tenant to let neighbors, etc. to use the pool when they are not there. Make it an addendum to the lease that the tenants will be evicted if they do this.
6) Have the tenant execute an agreement whereby they agree to indemnify you for any liability you suffer due to the pool.