How do I wash cloth nappies in hard water in the South East?

How hard is South East tap water, really?

South East Water says most of the water it supplies in Southern England comes from underground chalk aquifers, so the water is hard. That is geology, not a fault in the tap. Thames Water covers much of London and the Thames Valley and publishes hardness on each postcode quality report — one published zone example sits in the mid-200s mg/l as calcium carbonate, and the company states hardness across its area varies widely.

The Drinking Water Inspectorate classifies hardness in mg/l CaCO₃ and tells you to ask your company for the local number, because maps miss street-level changes.

MayTally is not publishing a ppm cut-off for nappies. If a blog gives you a single South East number, ignore it and use your postcode report.

How do I check hardness at my postcode?

1. 1
   Find who supplies the tap If you are not sure whether it is South East Water, Thames Water, Southern Water, Affinity Water or another firm, use the Water UK postcode finder.
2. 2
   Open that company's water-quality / hardness checker South East Water and Thames Water both ask for a postcode on their water-quality pages. The result is the figure to read against the detergent pack — not a screenshot of a neighbour's borough.
3. 3
   Read the pack row that matches that band and a dirty load UK Nappy Network says people in a hard-water area will probably need more detergent than in a soft-water area, and to start from the recommended pack dose, then adjust. No grams live here.
4. 4
   Judge the wash by the rinse, not by foam height DWI notes that hard water produces less lather from washing powders. A South East main wash can look 'not very soapy' and still be correctly dosed. Clear water at the final rinse is the check; a bubble-free main wash plus a wee smell is the sign to move toward the pack's hard-water / heavy-soil line.

Should I add Calgon or a jug-filter 'softener' to the nappy wash?

Do not invent a Calgon dose for cloth nappies. The UK Nappy Network do-not-use list — taken from manufacturer and retailer sites — includes Calgon, vinegar, fabric conditioner and several stain removers. If a nappy warranty already names what you may add, that label wins. This page will not give you a ml figure to pour on top.

DWI's hardness note is about kettles, scale and, if you install a domestic ion-exchange softener, keeping an unsoftened tap for drinking because those units swap hardness for sodium — a problem they flag for premature babies and low-sodium diets. That is plumbing advice, not a nappy-wash recipe. A jug filter does not turn a hard-water nappy load into a soft-water one.

• Powder first — NLWA and Nappy Alliance prefer powder over liquid for nappy loads; powder boxes print a hardness row.
• More water, not mystery additives — UK Nappy Network suggests extra-water or a longer, wetter cycle on modern machines, not a second chemistry product.
• Machine care — limescale is a drum-and-element issue; use the maker's maintenance cycle rather than dosing nappies with a descaler.

What does a hard-water nappy routine look like?

Same skeleton as the rest of the UK: dry-pail, a separate cold rinse, a long 40 °C or 60 °C cotton-type wash, extra rinse if foam survives, line dry. Which? still says wash at least every two days and skip conditioner. Hardness only changes how you read the box and the foam, not the need for a proper wash.

If nappies smell of wee when they come out 'clean', do not assume the South East needs a smaller scoop. Under-dosing in hard water is a common way to leave ammonia in the pad. If the final rinse is a bubble bath, rinse it out, then step the next dose down — the same suds rule as anywhere else.

Does hard water change which detergent the NHS allows?

No. NHS wording is that there is no evidence bio powders or fabric conditioners irritate a baby's skin. Hardness is not part of that sentence. Follow the nappy care label if it names bio or non-bio, and follow the pack for dose. Conditioner still stays off cloth because of absorbency, on the NHS changing page and on Which?.

In shortIn short: check your own company's hardness, dose powder from that row on the box, and believe a clear rinse more than a low foam head. Do not guess Calgon. South East chalk makes scale; it does not need a special nappy detergent brand.