Asbestos cement cold-water tanks — usually grey or black, square, with a heavy lid — were standard in UK lofts from the 1950s to the 1970s. The cement matrix locks the fibre in well, so an undisturbed tank is low risk; the hazards are mechanical. Tanks crack with age, grow brittle, and sit exactly where loft conversions, re-plumbing, boiler upgrades and
insulation top-ups need to work. Plumbers cutting into or breaking up an old tank in a confined loft is the classic exposure.