More than 300 state houses are sitting empty because of methamphetamine contamination, says Social Housing Minister Paula Bennett.
She estimates at least 370 houses are vacant and says five have had to be demolished because tenants are smoking or cooking P on the properties.
She says not only is the number alarming because houses are going unused, it's also concerning knowing that tenants are potentially smoking around children.
"It's a dreadful thing for kids and it permeates right throughout the house so the clean-up is so expensive," she told the Paul Henry programme this morning.
"It can take up to three months to clean them up."
She says her ministry is now testing more houses than ever before.
"We're testing far more than we were and even when the case manager goes in or tenancy manager goes in and sees or suspects that there might be usage of P.
"Any P smoking in a house actually has an effect on it."
Ms Bennett said people caught offending are evicted and cannot apply for another state house for a year but it's hard to catch people in the act as tenants must by law be warned if a case manger plans to visit.