Why has my water become cloudy?

The bottom-up clearing is the tell. Air bubbles rise, so a glass of aerated water clears from the bottom of the glass upwards. It usually follows work on the mains, a supply interruption, or cold weather, and it's a cosmetic problem rather than a safety one.

Sediment behaves the other way — it settles, so the water clears from the top down and leaves something in the bottom of the glass. Brown or orange water usually means disturbed iron or rust in the main, and United Utilities put it down mostly to historical sediment being stirred up in older cast iron pipework — which is exactly what a lot of the mains under Macclesfield's older streets still is. It typically follows nearby works, a burst, or a sudden change in flow.

Water quality in the supply is United Utilities' responsibility, and they'll want to know — they can tell you whether they've been working on the network nearby, and test if needed. If it's only one tap in the house that's affected, though, then the problem is your plumbing rather than the supply, and that's a plumber's job.

Worth knowing where it comes from in the first place: Macclesfield's water is drawn largely from the reservoirs in the hills right above the town — Lamaload, Trentabank and Ridgegate up in Macclesfield Forest — topped up from the Lake District and from groundwater. United Utilities name their local supply zones after those reservoirs, which is why your water quality report will say Lamaload, Ridgegate or Millbrook at the top of it.