My friend took a test this summer for a job. He drank a lot of water the day before and right before. The test came back negative for dilution. The only reason he got to take it again was because his cousin worked for the company. If you are trying to fool your parents, this might work...but if for a job..be careful, they are not stupid, especially if they send it to a lab...they will know if you have been drinking a lot of water....and will result in a failed test.