Phoslock Environmental Technologies first half revenues slumped 88 per cent as COVID-19 has lead to delays in many projects using its water remediation technology.

First half revenue fell to $1.2 million from $9.8 million at the same time last year, with the company noting its outstanding receivables are "higher than anticipated" as many customers blame the virus for late payment.

Phoslock has taken measures to cut costs including reduced manufacturing activity. Construction and commissioning of its new production plant will be re-staged and fast-tracked later when demand becomes more certain.

The company has a $380 million pipeline of work, including $200 million of Phoslock product sales and $50 million in engineering works in China.

Recent flooding in China has prevented the application of Phoslock due to unsafe, elevated water levels and this will result in a delay to those projects until such time as flood waters recede.