Mains

Mains is the drinking-water quality compliance register of a water utility's regulatory science team — the statutory evidence file that stands behind every glass of water the company supplies. It is not a dashboard about water. It is the record a regulator reads: every sample drawn from the distribution network, every determinand measured against its prescribed concentration value, every exceedance investigated to a named root cause, and the arithmetic that reconciles the whole year into a single return. The signature screen is the determinand compliance plate: one supply zone opened out as a full analytical certificate. Fifteen determinands run down the page — free and total chlorine, turbidity, iron, manganese, aluminium, lead, nitrate, trihalomethanes, coliform bacteria, E. coli, taste, odour, colour and pH — each carrying its prescribed concentration value, its unit, the number of samples analysed, the mean, the 95th percentile, the maximum recorded, the pass/fail arithmetic printed beside the row, and a stamped verdict of COMPLIANT, EXCEEDANCE or UNDER INVESTIGATION. The zone's overall compliance percentage is never typed in: it is produced in a single pass from the same counts the rows display, so the parts sum to the total by construction. Beneath the plate, one determinand's whole year is drawn as a chromatogram-style banded strip — one rectangle per sample, the prescribed concentration value ruled across it as a dashed line, and exactly one amber band breaking it. The caption tells the reader to count the bands, and the drawing bears it out. Around the plate sit the modules that make the register a working system rather than a report. The sampling programme shows required versus taken samples per zone and determinand with the shortfall risk classified in stated precedence order. Exceedance investigations carry detection date, repeat-sample result, root cause — mains burst, service reservoir ingress, a lead communication pipe, disinfection by-product formation, customer-side plumbing — containment action and regulatory notification status. Service reservoirs record inspection and cleaning intervals, turnover time and the last integrity survey. The lead strategy tracks properties still on lead communication pipes, the replacement programme and orthophosphate dosing. Operational monitoring lists works-outlet continuous monitors, alarms and calibration due dates. A sampling officer's round sheet runs the week stop by stop, and a login-gated analyst's laboratory portal holds sample chain-of-custody and the UKAS-accredited method register. The design is Swiss International Style scientific reporting crossed with a chromatography band plate: a cold laboratory-white ground, a hard twelve-column hairline grid drawn visibly on the page, enormous flush-left Familjen Grotesk headings against asymmetric white space, Inter Tight for interface and DM Mono for every figure with column-aligned decimals. There is no ornament anywhere. Colour is data and nothing else — a cyan, green and violet ramp reserved strictly for determinand classes, and a single alert amber that appears only where a sample has exceeded its limit. A live compliance ticker runs beneath the top rail, and every figure in it is derived from the register below rather than typed, so the rail can never contradict the plate it runs above. Navigation is a horizontal module rail; there is no sidebar. Remix Mains for any regime where measurements must be defended rather than merely displayed: environmental discharge permits, food safety sampling, air quality monitoring, pharmaceutical batch release, laboratory quality assurance, or any inspection record where somebody will eventually ask how the number was reached.