Despite this, Mrs Roberts was surprised by the positive P result.
"We didn't let them in as P smokers, whenever we went in the place looked perfect," she said.
They ordered a $269 baseline test to be carried out on October 25 to check if the house was contaminated.
The company took eight samples with one swab. The test returned a positive result of 2.3mcg - 1.8mcg higher than the current level which prompts a clean-up and 0.8mcg higher than the Ministry of Health's proposed national standard for carpeted properties.
Tony Buckley of Busy Bees Cleaning Services said the result either meant there were relatively low levels throughout the house which combined to give the 2.3mcg reading or it could all have come from one of the eight areas sampled in which case. " 2.3mcg is reasonably high".
Mr Buckley said the location and material where the meth residue was found dictated what needed to be done to remediate the property.
A spokesperson at Meth P Cleaning said the cost of decontaminating houses depended on many different factors including the materials of the house and the level of contamination but could cost between $1000 and $25,000.
Mrs Roberts had the house tested again on Monday at a cost of almost $1000, with individual swab readings in 11 sites around the property.
Mrs Roberts recommended that landlords get houses tested before tenants moved out.
"Get the P test done as soon as they give notice," she said.
The Ministry of Health last month released a report providing recommendations for the country's first national standard for methamphetamine contamination.
It said smoking rather than manufacturing meth meant there was a lower potential exposure to the drug on surfaces and a reduced risk of toxicity.
The proposed standard could be used as a guide until official new standards were developed by Standards New Zealand next year, the Ministry of Health said.
The tenants could not be reached for comment.
Current Health Ministry P-risk guidelines:
A contamination reading of 0.5 micrograms per 100sq cm or higher means a home needs decontamination
Proposed national standard:
0.5 micrograms per 100sq cm or higher where P was manufactured
1.5 micrograms per 100sq cm where P-used and carpeted property.
2 micrograms where meth has been used and no carpet.