Float valve

The water level in a pond always goes down during the summer because of evaporation or splashing from fountains. This is why you need an automatic level control system. Use a Basin FV-1 floater (1/2 po MNPT), which is mounted on one side of the pond. You can camouflage it by placing a flat rock on top. For drainage, use a 4" perforated pipe (French drain) on the side where the liner is lower.