I can promise you the sticks will not work if you dring too much water.

The sticks work much like the budget drug tests work. Drug tests also change color depending on what is in the urine.

If you drink plenty of water, anyone can pass on of those types of drug tests. There is just not enough actual urine in the pee to get a result. They test for this 'washing' of urine by measuring the level of creatine in the urine. If its too low, the test may not count.

The keosticks are very similar.

PS: This may or may not be from personal experience!