Tapware maker Methven today issued a profit downgrade, citing a range of factors, including the Christchurch earthquake.

The company said when it released its interim profit that full-year net profit after tax should be in line with the previous year.

It said today that it would be 10 to 15 per cent down on last year.

The reasons were a potential bad debt in Australia of $700,000, combined with fourth quarter trading weakness in Australia and New Zealand exacerbated by the latest Christchurch earthquake.

These factors were expected to reduce earnings by around 10 to 15 per cent on last year's net profit after tax of $7.8 million.

In addition, net debt was now forecast to increase by 15 per cent to 20 per cent on the prior year.

Methven is New Zealand's longest established, largest supplier and leading designer of showerheads, faucets and hot water valves to home renovators, plumbers and the building industry. It traces its history back to 1886.

Methven shares were down 2 cents at $1.60 shortly after the announcement.