Are the venomous? Have a look at the thread below (the scientific name of the false water cobra is Hydrodynastes gigas). Like most colubrids, H. gigas has duvernoy's glands. Yes it produces what is technically a venom. Has this been known to cause effects? Yes but even with prolonged chewing the bites cause mostly just localised effects (although more pronounce effects have been recorded in rare occassions). SO, at the end of the day they are technically venomous but the word venomous in this case does not mean the same as venomous does when talking about potent species such as elapids.