my brothers kids did the same kind of thing - they emptied a kitchen cuboard on to the living room floor to make a swimming pool

I can't remeber exactly what they used but it did include 2x 2l bottle of cooking oil, big bottle of ribena orange juice and whatever else they found

he had to take 3days off work cos he strained his neck shouting at them he did get the video camera out to film it too. summit to show them when they get older

little bastards

Cheers

Daniel