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Limestone contactors in horizontal FRP tanks

The DrinTec™ design of upflow limestone contactors of constant height simplifies the reload operation by means of feeding the granulated limestone continuously, under water and directly on to the limestone bed by a limestone feeding system, thus maintaining a constant bed height all the time.

It‘s a very effective system that operates continuously for many years without needing to perform a backwash.

DrinTec™limestone Contactors of constant height in tank feature limestone feeding system, internal perimeter spillways, underdrain system for water and air and built-in calcite silo.  Each unit is individually made according to project specific needs.

The designs allow for a guaranteed autonomy of more than 30 days and minimal wasted water if the outlet turbidity is properly controlled. This procedure has the advantage that the quality of the outlet water is always constant. Consequently, the operation and maintenance costs are reduced considerably over the traditional designs.

The limestone contactors are usually placed in parallel. Because they have the same height they offer the same counter-pressure. This facilitates the hydraulic design of the inlet manifold and provides an uniform and constant water distribution to the different tanks.

The limestone contactors operate by gravity with a low pressure drop, so they can operate directly with the outlet pressure of the reverse osmosis racks.

The turbidity is controlled using dust free material and maintaining a constant flow rate, i.e. avoiding sudden changes in flowrate. If the current flow is going to be increased, flow is initially diverted and incorporated gradually thereafter to the contactor.

There is very little need to purge the limestone contactors, as they operate upflow and do not tend to clog. However, at least once a year a 5 minutes sponging is recommended to reduce the risk of formation of preferential pathways.

Internal parts and the DrinTec™ process are protected by various patents.

Advantages of DrinTec™ limestone contactor process:

  • Designed to reduce the height and minimize visual impact
  • Vessels shipped in standard ocean container
  • Easy and fast installation
  • Very high efficiency
  • Flexible automation: fully, partial, none
  • Constant performance and water quality
  • Low maintenance cost
  • Minimum or no energy consumption
  • No moving parts
  • More than 30 days autonomy
  • No need for qualified workforce to operate
  • No need for frequent backwash: At start up and then once a year

Technical specifications

Máximum flow 1100* 1400* m³/d
Dimesiones deposito 4790 x 1625 x 2000 4790 x 1625 x 2250 (l x w x h) mm

Design temperature

40/65 ºC

Required material for operation

Granulated calcite & CO2 / H2SO4


Outlet turbidity

< 1 NTU**
Maximum inlet pressure 1 bar
Outlet pressure




>30 days

Time between backwashings

At startup and then every 6-12 months


Internal resin

For drinking water


External paint

UV light resistant


Manufacturing time

10-12 weeks


Manufacturing country



* May vary with permeate characteristics and water temperature.
** Assuming that the calcite quality is according to the recommendations in our technical brochure.

Canary Islands, Spain
+34 922 00 60 30

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