Arrange a survey covering space, water pressure and flow, the bypass, drainage and an unsoftened drinking-water outlet. Have the installer put the work and exclusions in writing.
Measure more than the cupboard
The cabinet must fit through the door and leave room for its pipes, hoses and controls. Check that you can lift the lid, add salt and reach the bypass without removing the appliance or emptying the whole cupboard. Leave access for a future repair or replacement.
For example, a unit that fits under the sink on paper may block the bin, trap or stopcock once the hoses are connected. Take photographs of the incoming mains and the cupboard, and ask the installer to measure the usable space rather than quoting from cabinet dimensions alone.
Ask them to check pressure and flow against the exact model's instructions. A home with several showers running together needs a different assessment from one with a single bathroom. Check the boiler or cylinder manufacturer's requirements and warranty before agreeing to softened-water connections.
Agree the pipework, bypass and drain routes
On a small screen, scroll the table sideways to see every column.
| Part of the installation | Question to ask |
|---|---|
| Incoming main and treated outlets | Which taps and appliances will receive softened water, and which will remain unsoftened? |
| Bypass and isolation | Can I isolate the softener and keep water supplied to the house? |
| Drain and overflow | Where will each discharge go, and does the arrangement meet the model instructions and applicable water-fittings requirements? |
| Power | Does this model need a suitable electrical supply, and is that work included? |
| Access | Can I refill salt and reach controls after everything is fitted? |
The Drinking Water Inspectorate advises keeping an unsoftened outlet for drinking when using ion-exchange softening. Confirm the drinking and cooking supply with the installer before work begins. An ordinary taste filter should not be assumed to remove sodium added by softening.
This is a survey checklist, not a pipe-connection diagram. The correct drainage and backflow-protection details depend on the equipment and installation. Ask a competent installer to check them against the instructions and local requirements.
What should happen before the installer leaves?
- Set the unit using the measured local hardness and the model's instructions.
- Check connections for leaks and confirm that the intended outlets receive the correct supply.
- Demonstrate isolation and bypass, so you know what to do if the unit develops a fault.
- Explain the initial setup, regeneration and any power-dependent controls.
- Show the approved salt type, refill procedure and maintenance schedule.
- Leave the model number, settings, warranty and contact details for faults.
Ask how performance will be checked after commissioning. A hardness test is more useful than judging success from how shiny a tap looks. Existing deposits may still need suitable cleaning; fitting a softener does not instantly remove them.
Choose an installer and compare the full scope
WaterSafe's register can help you find an approved plumbing business. Ask whether the installer has experience with the proposed softener and what happens if the survey reveals unsuitable drainage, pressure or access.
Your written quote should identify the unit, fitting kit, extra pipework, drinking-water arrangement and any electrical work. Ask whether commissioning and a handover are included. Read the UK cost guide before comparing totals.
Use the installation readiness checklist as a record of agreed answers. Ticking every box does not certify that an installation complies; it helps you identify what still needs confirmation.
Sources and installation checks
- DWI: hardness, softening and drinking-water provision.
- WaterSafe: approved contractors and water-fittings training.
- WaterSafe: find an approved plumber.
Always use the current installation instructions for the chosen model. This guide helps you plan a survey; it does not replace those instructions.