Silica is the quiet contaminant of purified water. It is only weakly ionised, so a conductivity meter barely sees it, and it is one of the first things to leak from exhausted ion-exchange resin. For a buyer specifying water for spirit reduction, that makes conductivity necessary but not sufficient.
Raw water is not a constant. Turbidity at one Delhi treatment plant swings from 25 to 8,000 NTU across the monsoon, disinfection by-products run higher every summer, and India's own groundwater monitoring shows nitrate exceedances rising after the rains. A distillery that proofs to a number cannot afford a water whose number moves — here is what shifts season to season, what survives the treatment train, and how to write a specification that holds in every month of the year.
A blending water specification describes what is in the water. It rarely describes what the water is held in — and demineralised water spends hours in contact with polyethylene, stainless steel and a handful of rubber seals before it ever meets spirit. Migration from those materials is regulated, measurable, and in one recent study the dominant source of organic compounds in a real distribution system was not the pipe at all. It was the gaskets.
A bottle of whisky holds a few hundred millilitres of water. Making the alcohol in it consumed ten to seventeen litres, and almost all of that leaves the distillery as effluent — acidic, copper-laden, and in India legally forbidden from leaving at all. Which makes blending water the one water stream in the whole plant that produces no waste, because it ends up in the bottle.
Nobody has published a microplastic count for whisky. But the evidence from bottled water, beer and soft drinks points somewhere uncomfortable and specific — the particles mostly arrive after production, from purification media, equipment and closures rather than from the ingredients. For a spirit reduced to strength with water, that makes the water plant and the bottling hall the whole of the exposure.
In a column still, live steam is injected straight into the descending wash, and steam sterilises the tanks and lines that later hold spirit and blending water. That makes boiler water a food-contact input in law — the US regulates the amines dosed into it by name and by parts per million in the steam, the EU by outcome, India by potability. Almost no distillery specification mentions it.