This concept changes the storing method of water - in larger quantities - from volume in concrete structures to volume in horizontal ø3m pipes. The concept is applicable in a number of existing and new tank storage systems, and the benefits are many, as regards both water safety, flexible volumes, easy access and self-cleaning. The solution is thus a great contribution to the UN SDGs #6 and #9.

The solution was designed in a partnership between Aarhus Water (project owner and end user), Arkil (civil constructor) and EnviDan (consultant).

Background
The utility company Aarhus Water is certified as a food company, due to the company’s handling of drinking water and has thus worked systematically with drinking water safety for more than 10 years. This includes focusing on preventing all types of pollution risks all the way from wellfield to consumer, including the design of new waterworks and water tanks.

Aarhus Water is in the process of updating several existing drinking water tanks to meet the service objectives in accordance with HACCP, and this combined with a need for adjusting the sizes of the tanks, led the project partners to look for new and different solutions.

Functional requirements
The tank design on each location should meet the following functional requirement:

• Water volume at each location
• Existing operating water level must be maintained
• Water volume must be divided into at minimum of two separate chambers
• Space for visual inspection or monitoring between water volume and surroundings for leak control
• Air space above water volume pressurized
• Pipes must comply with the requirements of "DK-Vand" and be approved after international migration tests.

The concept
In addition to meeting the functional requirements, the concept has the following benefits:

• Full control of the flow and retention time
• Each pipe has an inclination in the flow direction, thus the system is self-cleaning. Inside the technical building each pipe is equipped with a collection reservoir
• Each pipe can be operated independently and taken out of service as required, which gives a very flexible operation of the entire plant and ensure a steady water supply. The tank system is thus much less vulnerable to contamination and will provide an overall safer water distribution system. This is especially relevant in cities, where the water quality is sometimes affected by old and worn out tank systems
• The space between the two walls in the double walled pipes is pressurized with air for leakage monitoring and provided with drainage monitoring as well. This can largely reduce problems with leakage from the tank system, which is a big problem in many countries. And in case of leakage, the tank system will remain operational even though one pipe is closed for repairs.
• The cost is expected to be reduced by 30% compared to a conventional solution in concrete.

The result is a sustainable water management system to meet the SDGs, developed in a partnership (Vandpartner) between both builder, constructor, consultant and suppliers. By thinking smarter and focusing on sustainability a concept was formed, that will ensure clean water and flexible non leaking storage tanks for drinking water in the future. The pipes are produced in Latvia and supplied by Wavin.

The solution may not take giant technological steps, but nevertheless the solution has great potential for improving water quality and a stable drinking water distribution in both Denmark and the rest of the world. Though simple in its design, it is the simplicity that makes this concept so suitable for worldwide implementation.