Skip to content

Free Delivery on Orders over €25

To target the effects of limescale in your water, the Biotect Ultra SI may be your ideal solution. Compatible with Doulton-branded under sink and tap-mounted countertop water filter systems (KingfisherHIP DUO and HIP TRIO systems), it has a ceramic exterior with an activated carbon core and uses a limescale-inhibiting media to reduce limescale deposits on your appliances and metal surfaces in contact with your water. As with the Biotect Ultra filter from Doulton, the Biotect Ultra SI also reduces common contaminants in your water whilst retaining the minerals that benefit your health.

Alongside inhibiting the deposits from limescale, the Biotect Ultra SI filter also reduces:

  • Microplastics
  • Chlorine
  • Bacteria and cysts
  • Insecticides and herbicides
  • Heavy metals such as lead, cadmium and mercury.

For more information on our testing data for the Biotect Ultra SI, please visit our test data page.

If you are looking to specifically target contaminants of concern in your water, you may want to explore our DUO and TRIO under sink systems that allow for enhanced targeting with add-on cartridge options.

You can also take our water quiz to find out the best fit for your needs.

49mm 49mm 254mm
A bio tec ultra replacement water filter

1 x Doulton Biotect Ultra SI (2505) Filter

Technical Documentation

Download instructions and test reports.
Product Instructions

Biotect Ultra Si 2505 Filter Product Instructions

Biotect Ultra Si 2505 Filter Product Instructions

Free shipping is available on orders over £25/€25.

Next working day delivery is available for orders placed by 11:00 (Monday to Friday), subject to the destination and courier availability. Orders placed after this time will be processed on the next working day.

Additional details and options specific to your country will be provided at checkout.

Discover more in our FAQ

How often should I replace the filter in my Doulton filter system?

We recommend replacing your filter every 6 months. If you notice a drop in water pressure or a change in taste, it may be time to replace the filter. You can try cleaning the filter first, following our guidelines if you notice any changes earlier than 6 months. How to clean a ceramic water filter (Youtube)

What systems is the Biotect Ultra Filter SI compatible with?

The Doulton Biotect Ultra SI filter is compatible with all Doulton under sink and tap-mounted countertop systems. They are designed for use with any system that has an M12 fitting. If you would like to use a Doulton filter in any other brand of system, please check with the manufacturer directly for compatibility.

Can I set up a subscribe and save service for Doulton filters?

We do offer an subscribe and save service. Please head this page to sign up and enjoy automatic replenishment of your filters, alongside an exclusive discount.

Advanced Filtration Technology
Eco-Conscious Hydration
Doulton water filter banner

Your water worries may be due to contaminants in your water...

Take our quiz to find your ideal solution, or click the button to read our contaminants guide.

Take the quiz Contaminant Guide

Customer Reviews