Which test will test positive for methadone?

Methadone does not show up in a basic opiate test which can detect heroin, codeine and morphine (and perhaps oxycodone, hydrocodone, and dilaudid). A Methadone specific test must be performed to detect Methadone.

It depends on what kind of a test your PO is doing. If it's an instant test, then MAYBE not, no guarantees there, but methadone, as well as other more specific opiates must be tested by a lab. If they send it to a lab, then they probably do test for it. Play it safe and drink a lot of water from now until the test.

Drinking Water is a myth when it comes to preparing for any urine test. Most labs will be able to identify the high water content in your urine and determine you tried to dilute the specemin which will not look good for your PO. However, unless they specifically test for methadone it will not show up in a standard urinalysis. While the chemical composition is opiate based, it breaks down very fast and will not likely be detected. I would be more concerned about the heroin you took that required you to take methadone in the first place.