DWT — Water Treatment, Explained

The agencies have already published the warning for 2026-27: a strong El Niño and rising odds of a dry summer. How many days of water the farm should hold, what an open dam loses to the sky, what a shed roof can harvest, and the registrations that keep it all legal.

Export fruit is washed, cooled and moved in water, and the audit schemes treat every litre of it as food contact. What GLOBALG.A.P. and South African law require, how a recirculating dump tank is kept safe with chlorine and pH control, and why Listeria changed the rules for hydrocoolers.

A broiler drinks nearly twice what it eats, through kilometres of warm plastic pipe where biofilm grows readily. The water-quality numbers for birds and pigs, the chlorine-and-pH discipline at the far nipple, and the between-flock line clean that decides the next cycle's performance.

The law treats a milking shed as food premises, and the water that touches milk equipment must meet the drinking-water standard's microbiology. What the regulations require, why hard water grows milkstone, how iron eats your sanitiser, and the plate-cooler water worth catching.

Injecting fertiliser through the irrigation system saves labour and puts nutrition exactly where the roots are, until calcium meets sulphate in a stock tank or fertiliser syphons back into the borehole. Injection equipment compared, the mixing rules, and the backflow protection the law expects.

The few hundred litres in the spray tank carry the priciest chemistry on the farm, and hard, alkaline or muddy water quietly cancels it. How hardness ties up glyphosate, why some insecticides break down in the tank within minutes, and what to test and fix before blaming the product.

A dripper's water passage is under a millimetre wide, and the crop guideline tolerates twenty-five times more iron than the emitter does. The clogging hazard numbers, the one-tenth filtration rule, choosing between screen, disc and media filters, and the chlorine-and-acid maintenance that keeps lines alive.

An irrigation analysis answers four questions: will the salt cost yield, will the sodium seal the soil, will an ion burn the crop, and will the water damage the equipment. The South African guideline numbers that answer each, in plain terms.

A dairy cow in milk drinks five litres for every litre of milk she gives, and tolerates only a third of the salt a dry ewe shrugs off. The official South African numbers per species (how much water, how much salt, and the handful of real poisons) plus the trough habits that protect the herd.

Surface water is weather you can pump: clear one week, mud the next, and in a hot dry autumn it can grow something that kills cattle overnight. What turbidity and blue-green algae do, and the treatment steps that turn a dam into a reliable supply.

A drought reaches your borehole months after it reaches your lands. When it does, both the amount of water and the water itself change. Why last year's lab certificate stops describing the water, how to find out what a borehole can sustain, and how to treat what comes up.

Steam boilers concentrate whatever the feed water brings. The published feed and boiler-water limits for shell boilers, when softening alone stops being enough, and why the AIA inspection is where poor water treatment gets caught.

Beer and soft drinks are mostly water, and the water is a recipe ingredient. Why alkalinity is the number brewers fight, why trace chlorine ruins batches at parts-per-billion, and how bottlers specify their treated water.