Do you have a sand filter?
The most common source of leak in pools is your sand filter. Once the gasket under the backwash handle has perished, water can travel down through the backwash/waste line during normal filtration operation, resulting in tremendous water loss in a short period of time. Your local pool shop can do this simple repair by replacing the internal gasket.
If you have a pool, spa and or water feature all connected on the same system, they will need to be isolated to determine which is leaking.
It is natural for your pool to lose a degree of water to splashing, to backwashing and evaporation, its when your having to top it up more than 3 inches a week you may have a problem. Follow a simple guide to confirm that you have a leak prior to calling us out.
The "Bucket Test" will determine if water loss in a pool is due to evaporation or a leak:
After 24 hours, compare the two levels. If the pool water drops faster than the bucket then you have confirmed that you have a leak.
Call Paul 0400 282 000