Let’s do some back of the envelope calculations here… Looks like about 1m x 3m x.5m deep. So that’s 1500 kilos. Of course if it’s actually bigger or deeper that is significantly greater. eg. 1.2m x 3m x .6m yields 2,150 kilos.

Basically anything deeper than ~12 cm exceeds the design strength mandated by building codes (60 lb/sq design load x 1 lb/ft/47.8803 Newtons x 1/.102kg (at normal gravity) So half a meter deep approximates 4x the design strength.

edited to add…somewhere those calculations are off. we can avoid the unit conversion with the simple fact that 1 cubic foot of water is ~62 pounds. So 1 foot deep is just over the design limit and 2 feet would be double the design limit.