Most of us believe the home tests are accurate. If you can pass your first void of the morning, you are good to go without much dilution. If you pass your home test in the middle of the day with dilution, then you should dilute before your test. Because dilution will lower your creatinine and specific gravity, you need to make sure you allow for that and make sure that you take extra creatine (starting at least 48 hours before your test) and drink gatorade instead of water.