Letters: Water is clear

Wednesday November 20, 2019 Published in Letters to the Editor
Clear water is also needed for UV disinfection says a letter writer. Clear water is also needed for UV disinfection says a letter writer.

Dear editor,

In October, government announced the importation of polyaluminium chloride (PACl) – a chemical to make water ‘clear’. Clear water is more appealing to drink; and better for cleaning and washing.


Clear water is also needed for UV disinfection. PACl causes silt and fine particles to clump together and form a jelly-like sludge; high in aluminium. Consultants have proposed trucking this sludge to Arorangi in sealed containers (to prevent leakage).

But there has been no geotechnical investigation of the dumpsite; no construction of long-term storage; and no consultation with the Arorangi community. Also, no truck. Water clarity has not been monitored, so engineers cannot estimate how much sludge will be produced. Based on the South African average, the 10 Te Mato Vai systems could generate up to 1,500 tonnes of sludge a year.

When sludge is cleared from the settlement tanks, PACl wastewater will be discharged into the stream. This will increase aluminium levels in our waterways; potentially our wetlands and lagoon. Aluminium damages aquatic species’ respiratory systems.

The good news is that chemicals are not needed. In dry conditions Rarotonga’s water is already clear. Instead of a system dependent on chemicals that generate toxic waste, divert water that doesn’t meet the required standard. Collect water when the streams are clear. Don’t collect the muddy water.

Anna Rasmussen

Chair, Te Vai Ora Maori.

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