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Drinking Water Supply Streams

How much water do we abstract/pump out of the streams?

The Waiorohi is the larger of the two water supply source waters.  The average flow in the Waiorohi Stream is almost twice that of the Tautau. Tauranga City Council has a consent to abstract up to 37,000 cubic metres a day from the Tautau and up to 54,000 cubic metres a day from the Waiorohi.  The treatment plants themselves are capable of producing 34,000 and 33,000 cubic metres per day respectively.  On average they process 15,000 to 25,000 cubic metres per day each, depending on demand.

Why don’t the streams run out of water when it doesn’t rain?

When standing on the stream banks, it does not take much science or experience to notice that both the Waiorohi and Tautau streams are very “skinny”.  They are insignificant in size when trying to imagine how they could be responsible for supplying over 120,000 people with their daily domestic and industrial potable water supply.  When noting the small amount of water flowing in the streams, one would think it would not take much of a dry spell before the stream flows dropped to inadequate levels.  This would be true.  Thankfully the streams are spring fed. As a result both streams have a relatively steady base flow all year round. 

What is a Drinking Water Supply Intake/abstraction point?

The intake is that point on the river, including the plant and equipment (such as weirs, screens, pumps etc.) where the Council abstract water from the river and pump it to the Water Treatment Plant where it is purified to a very high standard.

The Waiorohi Intake

Originally water was taken from two points along the Waiorohi. One weir, built around 1965, and situated 3km upstream of the Oropi Road Treatment Plant diverted water into a pipeline which then fed the water by gravity down to the plant. The second weir situated immediately below the Treatment Plant pumps water up to the plant. The gravity pipeline was eventually abandoned due to similar reasons as the original Tautau gravity main (see below). Today all the water from the Waiorohi is pumped to the Treatment Plant from the second weir. Screens prevent debris from clogging up the pumps and generators kick in automatically to avoid any water shortages from occurring in the event of a power disruption. 

 

Wairohi Stream Aerial Inspection May 2010

Waiorohi Intake

The Tautau Intake

Water is taken from the Tautau Stream at a weir five kilometres away from the Joyce Road Treatment Plant. The weir was built in 1958 and water was gravity fed to the treatment plant. However, the gravity pipeline became a constant cause for concern. It was laid through a narrow gorge where it was difficult to access and was often damaged by slips. So in 1989 the intake at the weir was upgraded to include a pumpstation which pumped the water to a raw water reservoir situated on a highpoint. Water is then gravity fed from the reservoir through a pipeline down to the treatment plant. The raw water reservoir, having a capacity of 4,500 cubic metres, is able to smooth out the fluctuating demands of the treatment plant. Screens prevent debris from clogging up the pumps and generators kick in automatically to avoid any water shortages from occurring in the event of a power disruption.

 

Tautau Stream Aerial Inspection

Tautau Intake


Last Reviewed: 17/02/2017