Softened drinking water: sodium, kitchen taps and baby feeds
By Limescale Logic · Updated 8 October 2026 · Editorial policy
Before fitting a salt-regenerated ion-exchange softener, agree which tap will supply drinking and cooking water. An unsoftened cold drinking-water outlet is a practical part of the installation plan, rather than something to discover after the kitchen has been connected.
Ask the installer to identify the unsoftened drinking and cooking supply, label the arrangements clearly and demonstrate the bypass. Do not assume that a separate filtered tap is unsoftened: it may be fed from either side of the softener.
What changes in an ion-exchange softener
With a sodium-regenerated ion-exchange softener, hardness ions are exchanged for sodium. This is a different process from taste filtration. How much sodium the treated water contains depends on the incoming water and the amount of hardness removed; the salt bag's size does not tell you the sodium concentration at the tap.
For a model-specific assessment, ask for the untreated supplier information, the proposed outlet arrangement and any relevant treated-water results. A household hardness test can demonstrate hardness reduction; it is not a sodium test or a general drinking-water safety test.
Baby feeds and individual dietary advice
DWI's domestic-treatment guidance says artificially softened water should not be used to make up baby feeds. Follow the current NHS preparation instructions and use the appropriate water source; do not substitute a filter's marketing claim for that advice.
If someone has been advised to limit sodium, ask the healthcare professional responsible for that advice about drinking water. Provide the actual water information and installation details. This guide cannot decide whether a particular treated supply fits an individual's medical needs.
Map the outlets before fitting
| Outlet or connection | What to establish |
|---|---|
| Kitchen drinking tap | Is it supplied before the softener, and how will it be identified? |
| Separate filter tap | Is its feed softened or unsoftened, and what does the exact cartridge claim to reduce? |
| Boiler filling connection | Does the proposed connection comply with the exact boiler manufacturer's instructions? |
| Bypass | How is it operated and what changes at the outlets when it is used? |
Keep the outlet map with the installation paperwork. This helps later occupants and plumbers understand the system. A filter cartridge does not automatically remove sodium; require a specific, supported claim for the complete system if that is the intended purpose.
If a softener is already installed
- Find the installation manual and any plumbing diagram.
- Ask the installer or a qualified plumber to confirm which cold taps are unsoftened. Do not infer the pipe route from taste alone.
- Identify the model and type of any separate drinking-water filter.
- Ask how the bypass affects each tap and whether any appliance settings need attention.
- Record the confirmed arrangement and tell other people in the home which tap to use.
If the outlet arrangement cannot be established, seek advice before relying on a particular tap for an infant feed or a dietary requirement. Do not attempt a plumbing alteration based on this article.
Keep separate water concerns separate
A softener is not a general disinfectant or a guarantee against contamination from household plumbing. If colour, smell or taste changes suddenly, contact the supplier and follow any current advice. If the concern is lead pipework, see lead testing and precautions.
Before purchasing, use the installation checklist and compare softeners with filters. Each guide addresses a different decision.
Sources and scope
- DWI: domestic water filters and softeners
- NHS: making up baby formula
- DWI: water hardness and softening
- NSF: water-treatment standards
Source guidance checked 8 October 2026. Manufacturer examples apply to the named products and do not replace your own model's instructions. This is a researched guide; no hands-on product test or individual medical assessment is claimed.