Testing is not an optional extra
Private water can come from boreholes, wells, springs or other supplies, and the safe use depends on source protection, treatment, monitoring and local responsibilities.
What to ask
Ask who is responsible for the supply, what testing has been done, what parameters were checked, whether treatment is maintained, whether the supply is for domestic or public/commercial use and what the local authority expects.
Publication boundary
Do not tell readers water is safe from appearance, taste or a single anecdote. Treat drinking-water content as high-risk and location-sensitive.