On hard water and hair, the science is mixed and narrow. The most cited study is a 2016 Pakistani experiment. The experimental group of hair samples was treated with hard water from district Kohat for 10 minutes on alternate days for three months, while the control group was treated with de-ionized water, with tensile strength measured using a universal testing machine and compared using a paired t-test.

In that trial of 76 men, hair treated with hard water for three months showed a significantly lower mean tensile strength (238.49) than hair treated with de-ionized water (255.36), with a P value of 0.001.

Critically, the authors themselves drew a line the viral version does not. The study's own background states that hard water is thought to play a key role in weakening of hair (not hair loss) and breakage.

A separate controlled experiment reached the opposite conclusion. A study involving 15 female participants found that after 30 days of immersion, hair samples in hard water showed virtually identical tensile strength and elasticity to controls.

A review of the evidence concluded there was no significant difference in hair strength or elasticity between the two water types, that evidence on hard water and hair damage is inconclusive, and that mineral deposits may worsen hair condition and indirectly contribute to shedding but are unlikely to be the main reason hair is falling out.

Even the commercial sites selling the solution concede the hair loss part. One Dubai water treatment vendor states that hard water can cause increased breakage and shedding due to mineral coating, dryness, and scalp irritation, but that it is not a direct cause of clinical hair loss (alopecia).

Another states that hard water does not cause genetic or hormonal hair loss, though it can make shedding worse by weakening strands and roughening the cuticle.

A third acknowledges that hard water can weaken the hair shaft and promote breakage over time, but that there is no good evidence it causes the follicle to stop producing hair, and what appears in the drain is far more likely to be broken strands than shed roots.

On Dubai's water specifically, the "hard water" premise is contested. Dubai's supply is desalinated seawater, and desalination strips minerals out before partial remineralisation. Dubai uses advanced desalination systems including reverse osmosis, multi-stage flash, chlorination and remineralisation to produce water meeting WHO standards, with tap water TDS typically in the 70 to 120 mg/L range.

A technical discussion of Dubai water notes that almost all water there is desalinated seawater, including 99 percent of locally produced drinking water, and therefore has super low hardness in general. By contrast, a water treatment company claims DEWA-supplied water hardness generally ranges from 100 to 200 mg/L as calcium carbonate, which it classifies as moderately hard. Regulators place the scaling threshold higher: Australian guidelines state total hardness above 200 mg/L may lead to excessive scaling, and the WHO guidelines identify water at or above 200 mg/L as scale-producing while water at 100 mg/L or less is considered soft and more corrosive to pipework.

UAE authorities and quoted experts have addressed this exact folk belief. The National reported that hair loss, dry skin and premature ageing are among the problems blamed on UAE tap water, that experts dismiss them as myths people have clung to for too long, and that the official government line is that desalinated water in Dubai and Abu Dhabi is fit for drinking, even unfiltered, and for washing.