Apex Water was engaged to complete an upgrade to the 4.4MLD Braemar water treatment plant to remove arsenic from the spring water and achieve compliance with the NZ drinking water standards. The plant was also operated for three months following commissioning.Design risk was mitigated through the completion of site trials to confirm the effectiveness of the adsorption media. The scope of the upgrade included supply and installation of a feed pump station, four pressure filters with media for arsenic removal, new duty/standby UV disinfection units, spent backwash discharge system, and chemical delivery apron for delivery and storage of caustic soda, sulphuric acid and HFA. A new building to house the plant was also constructed.Construction works had to consider the site not only being operational but also being located in a public area used for recreation. Extensive fencing, signage and the use of security cameras were employed. Appropriate methodologies were used to progress works over the winter months.