Randy Truby, comptroller of the International Desalination Association, says that advances in manufacturing processes have allowed 450 sq ft of membrane to be crammed into each cartridge, compared with 300 sq ft when they first came on the market. But treating seawater still requires pressure of about 80 bar, 40 times more than car tyres. That is why treating seawater is more energy-intensive than brackish or waste water, which require less force.