This guide was written by Keith, a mechanical engineer with over 20 years of hands-on experience working with reverse osmosis and water filtration systems.
A practical, plain-English guide by FilterAuthority.co.uk
No over-engineering. No scare tactics. Just staged filtration explained clearly.
If your home uses a private water supply, such as:
…your water is not treated the same way as mains water.
This guide explains what off-grid water can contain, what UK private supply owners are responsible for, and how to choose filtration that actually makes sense — without over-engineering or scare tactics.
Off-grid water means your supply:
Private supplies are common in:
Unlike mains water, you are responsible for the safety of your supply.
Private water can be excellent — or problematic — depending on location.
Common issues include:
This is why one-size-fits-all filters do not work for private supplies.
In the UK:
Many owners choose filtration even without a failed test, simply for peace of mind.
Always filter in stages — never rely on a single filter.
A proper setup usually looks like this:
Sediment → Carbon → Disinfection (UV or RO)
Removes:
Protects everything downstream.
Reduces:
Carbon also protects UV and RO systems.
Good for:
Usually installed at the kitchen tap only, not whole-house.
Sediment → Carbon → UV
Sediment → Iron removal → Carbon → UV
Sediment → Carbon → RO (kitchen tap)
Sediment → Carbon → UV + RO at tap
Often yes — at least partially.
Whole-house filtration protects:
But drinking water usually benefits from a separate RO or carbon system.
Sometimes — but it depends entirely on location and testing.
If bacteria is a concern, yes.
No — RO is normally for drinking water only.
It kills bacteria but does NOT remove chemicals.
They can — especially near industrial or military sites.
If this feels confusing, you're not alone.
That's exactly why FilterAuthority provides:
The Assistant helps match filtration stages to your supply.