Luke McArdle, the director of McArdles Cleaning and Restoration, said his company had also tested a house in Bathurst and two in Oberon this year for traces of methamphetamine [ice].

Mr McArdle said increasing use of the drug, by both smokers and people making it in illicit laboratories in residential houses, posed health concerns for innocent future tenants of the properties and legal liability concerns for the unaware owners of the houses.

"We have probably had two or three with positive test results," he said.

He said they had tested a house for sale on the outskirts of Orange this year for meth contamination at the request of a potential buyer of the property. It had tested negative.

Mr McArdle said the contamination is spread through the houses through vapours that become airborne and liquids which get absorbed into porous materials including ceilings, walls, carpets, furnishings, drains or ducting systems.

He said the contamination from high levels of drug use could result in both chronic and acute health effects ranging from nausea to causing brain, liver, heart, kidney and lung damage, and even death.

"It is such a bad drug," he said.

Mr McArdle said in some cases remediation of a contaminated house involved having to remove walls back to bare studs and remove airconditioning ducting with the procedure costing at least $30,000.

He said if the chemicals had been disposed of down toilets or drains there would be wider contamination outside the house.

Mr McArdle said while meth-use risks had previously been an issue in Sydney and major cities, increased use of the drug was now posing threats in regional areas.

McCormack Barber real estate director Peter McCormack said his firm had about 20 per cent of the rental market in Orange but he had not seen any cases.

"We've had no reportable issues," he said.

However Mr McCormack called on the state government to introduce mandatory testing of properties after each tenant finished their lease.

He said a test should be at the owner's expense and it would determine which tenant was responsible.

Decontamination of a meth-infected house starts with a simple detection test but it can become very involved if there's a positive finding.

Luke McArdle, the director of McCardles Cleaning and Restoration firm, said the initial 'yes or no' test cost $600-$1000.

He said staff examined a small area of a wall, often only 100 square millimetres.

Mr McArdle said traces could often be found in walls and particularly around ceiling air vents and ducting for airconditioning.

He said it could be spread throughout a house even from the drug user touching door knobs and electrical switches.

Mr McArdle said if a meth laboratory had been in the house the testing costs would rise to $1500-$2000 depending on the contamination.

But getting rid of the contamination can blow out to at least $30,000 if walls have to be removed back to the bare studs.

After being cleaned with a peroxide foam, detergents and water they would then need to be replaced and repainted.

He said any porous material, including lights, carpets and curtains could soak in the drug's vapours and they might need to be removed in the cleaning process.

Decontamination can also involve the removal of all the ceiling insulation and vacuuming the entire ceiling cavity.

Timbers also might need to be treated with weak acids.

Mr McArdle said pipes needed to be flushed, the property well-ventilated and houses needed to be steam-cleaned or high-pressure cleaned.

Workers need to wear protective equipment including gloves, coverall clothing, booties over work boots and either full or half-face respirators with protective eye wear.

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