The Hutt Valley District Health Board says there is little it can do to reduce cannabis getting into its mental health unit.
A former patient has spoken out, saying cannabis is regularly used by patients and it's often smoked only metres from a nursing station.
Lyn Copland, whose son is in the unit, spoke out last week claiming patients had regular access to recreational drugs because the unit is understaffed.
Now a former patient, who won't be named, says cannabis was readily available in the unit, with one patient taking orders and delivering marijuana to others in the ward.
She says there's little or no visible effort to stop the drug use.
Hutt Valley District Health Board chief executive Graham Dyer says visitors caught with drugs get a trespass notice, but patients who are caught are likely to be put under tighter security.
He says drugs are usually brought in by voluntary patients, who staff are not allowed to search.
Mr Dyer says the unit's open policy is there to make people with drug or alcohol issues feel comfortable seeking help there.
Meanwhile the clinical director of Hutt Hospital's mental health unit says the accessibility of cannabis at the unit is a wider problem not restricted to the Hutt Valley.
Wolfgang Kure says many patients believe cannabis will help their condition, when in most cases it slows down recovery.