Mairangi Bay, New Zealand

Kowhai Reservoir is located in Mairangi Bay, Auckland and can hold 4.6 million litres of water. It serves a population of 16,500 residents from Browns Bay in the north to Campbells Bay in the south. What’s more, it’s 7 metres high, 28 metres in diameter... and is 63 years old. Sikadur Combiflex (high performance joint sealing system) had been installed in the floor, wall and corner joints of the reservoir during the 1990s, so after 30 years of service it was due some remediation.

Project Requirements

After a thorough inspection it was determined that the new generation Sikadur® Combiflex® SG System should replace the 30 year old Sikadur® Combiflex® previously installed in the reservoirs vertical and horizontal joints.


Working inside a reservoir has inherent challenges. The sheer height of the walls (7 meters) meant a scissor lift was the only way to both remove the old joint sealing system, prepare the joints and install the new Sikadur® Combiflex® SG system.

Sika Solution

The Sikadur-Combiflex® SG System was the ideal solution for this project due to its high performance and movement characteristics, and it’s certified approvals for use with drinking water. It is a versatile, high performance, joint and crack sealing system for construction joints, expansion (movement) joints, connection joints or cracks. The system allows variable and high levels of movement in one or more directions, while maintaining a watertight seal.

Sika Products

Sikadur® Combiflex® SG-20 P

Project Participants

Specialist Contractor
Sansom Construction Systems Ltd

Product Specifier
Dominic Sulisfianto

Main Contractor
Cassidy Construction