I quit smoking marijuana two weeks ago and I have been drinking massive amounts of water to flush my system will I be clean for a drug test?

Depends. Light use, single exposure, likely gone. Chronic user and or heavy use, can persist for months. The drug attaches to fat cells in your body and begins to detach and leave you over time as long as you quit using. You can't really flush it and internet coaches that promote various products to do so are frauds.
Do not count on it . With the current medical technology in place, marijuana may be detected in the urine even months after one last used the drug. The best way to pass a urine drug test is very simple: don't use drugs.