Primer should be low VOC, Epoxy based.

AQUASMART-DUR: The unique characteristics which distinguish this primer from the other are the following:
It is highly effective humidity barrier. So, it is ideal for applications subject to negative pressure/ rising humidity.
When it is used as a negative pressure humidity/ vapor barrier its total consumption should be at 0.5kg/m2 in 2-3 sequel coats.
It is non-flammable and zero VOC.
You choose this primer to apply over strong and sound concrete in order to increase adhesion and to close any Ω holes.
AQUASMART-DUR is also an easy applicable (water-based) solution for application over iron, galvanized steel, aluminum, concrete, screeds and wood.

Note: If outside the tank there is waterproofing of the concrete, AQUASMART-DUR can be applied in 1 single coat of 0.2kg/m2.
If there is not any outside waterproofing and concrete protection (or there are doubts how effective it is), AQUASMART-DUR should be applied in 2-3 sequels coats at a total consumption of 0.5-0.6kg/m2!

Main Coat is HYPERDESMO-2K-W

HYPERDESMO-2K-W is a solvent free, thixotropic, two component coating, based on high quality elastomeric polyurethane resins. After polymerization, it produces a strong flexible-elastic membrane completely impermeable by water. It has excellent resistance to acidic and basic environments and performs even in tanks containing chlorine treated water. The material polymerizes into a shiny compact membrane that does not allow the growth of microorganisms or bacteria which is a big problem when the waterproofing material is a cementitious or other highly porous material. The product is certified according to the latest requirements of European Union for potable water tanks.

In this sample HYPERDESMO-2K-W is applied in one single coat of 1.4kg/m2 and present the way you apply the material over horizontal surfaces.
On vertical surfaces this total consumption of 1.4kg/m2 can be achieved by applying 2 sequel coats of 0.7kg/m2 each.