They fake plumbing problems, do a shoddy job and even resort to bullying customers .

They will pretend your bathroom has a problem, do a shoddy job or even use bullying tactics, victims say.

These are the rogue or dodgy plumbers who terrorise some Singapore households.

Before this year, the Singapore Plumbing Society (SPS) received two to three complaints a week about such fly-by-night crooks.

There are still complaints now, said Mr Chia Wai Chon, SPS' operations manager.

"They usually don't have a company and give out only their cellphone numbers. They quote cheap prices over the phone, like $50, but when they arrive, they say the job may cost $150 or $200," he said.

As of last month, the Consumers Association of Singapore (Case) had inquiries or feedback involving 64 plumbing cases.

It received 127 such cases in 2007 and 158 cases last year.

Case cited how a consumer paid $220 to a plumbing vendor to repair a heater. Two technicians turned up.

The vendor then told the consumer to wait three days before switching on the heater.

When he finally did turn it on, he found that the heater had not been repaired.

There are two types of plumbing work: sanitary and water service.

The former involves work on existing water pipework and sanitary fittings such as toilets, urinals and basins, while the latter refers to work related to new water pipework and fittings for water supply.

Prior to 2002, the Public Utilities Board (PUB) gave out licences to registered plumbers to carry out all sanitary plumbing work.

Licensing was removed in 2002 to open up the market to allow house owners and property developers a wider choice of plumbers to carry out sanitary plumbing work.

Said a PUB spokesman: "Minor sanitary work such as the replacement and repair of sanitary fittings and pipes in existing premises is not complex and similar to the fixing and repair of many other household fittings such as air-conditioners. It can be carried out by a general contractor skilfully."

She added that the installation of new sanitary pipes and toilet facilities is still regulated by PUB.

Some plumbers say this lack of a licensing requirement now has given rise to the bad hats.

Said plumber David Chi, 48: "Plumbers without a licence may not be aware of the proper procedures and might do shoddy work."

Another plumber, Mr Abdul Ghafur, 51, has had to repair shoddy work done by others.

He said: "Undersized pipes used may cause the water pressure to be too low. It really gives the industry a bad reputation."

At least one disgruntled customer has made a police report.

Housewife Lee Yee Ling, 31, said she contacted a plumber to help her fix a leaky water heater.

He refused to quote a price over the phone.

When he and another man turned up, they said her sewage pipe was also leaking and her repair bill would total $400.

Said Ms Lee: "I thought it was very expensive. I could not contact my husband on the phone so I ended up telling them to go ahead."

A few minutes later, she called up a friend who told her to stop the repair work.

But the men refused to do so, even though they had not yet started. They even threatened her with a spanner.

"They got angry when I said I was going to call my husband and even went ahead and did some work on my heater and sewage pipe so I had to pay up," she said.

Ms Lee later made reports to the police and Case.

A PUB officer confirmed that the sewage pipe had not been leaking in the first place.

Ms Lee has since received a $350 refund.

She said: "I'm still very angry. People should be careful when they engage plumbers."

Consumers can contact the SPS hotline on 6294-9252 or the NTUC Income hotline on 6788-8788 for referrals to authentic plumbers.

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This article was first published in The Straits Times.