Data Centre Water Treatment Principles
Introduction
Data Centres Water Treatment is critical for data centres that process and store our internet data. Up time is critical with 99.999% as a standard. Data servers emit large amounts of heat and they need to be cooled. Cooling systems and water treatment systems need to be designed, operated and maintained up to a very high quality standard. Problems such as corrosion, scale, Legionella risk, and biofouling that come with water being used as a cooling medium, need to be managed intelligently.
Cooling Water Needs
Water is an extremely efficient and cost-effective medium for cooling data centres due to its high specific heat capacity compared to air. This means that water can absorb more heat without experiencing a significant temperature increase according to the formula Q = mC(Delta T). For instance, let’s consider the amount of water and air required to cool an 8kW server rack. While 3200 m3/hour of air would be needed, only 2 m3/hour of water would suffice, demonstrating the significant difference in heat transfer efficiency. However, water is a precious resource and it needs to be managed sustainably. This required indepth design and operational know how. Some data centres use evaporative cooling towers some use adiabatic cooling towers in colder climate countries where water cooling is needed only in the summer.
Some data centres use Cryogenic Liquid Nitrogen cooling systems that operate at very low temperatures down to -196 degrees C. At such low temperatures, high tech chip energy efficiency can improve by a scale of x 4. The liquid nitrogen then carries the heat and offloads it to some fluid like water, glycol or a mix of the two.
Humidification of Air in Data Centres
Another use of water in data centres is for maintaining a certain level of humidity in the atmosphere in data centres which would prevent the air from becoming too dry which can lead to the formation of static electricity which can have a detrimental effect on sensitive electronics. Demineralized sterile water is normally used in humidifiers. To produce demineralized air you need to treat potable water with RO or with a mixed bed ion exchanger system.
Fire Fighting Systems
Misting fire suppression systems are effective for data centers because they use a fine water mist to extinguish fires with minimal water damage and minimal space requirements compared to traditional systems. They work by cooling the fire and displacing oxygen, and can be designed to discharge only in the area of the fire, not the entire room. These systems are also often more cost-effective, environmentally friendly, and require less maintenance. They are:
Cost-effective: Misting systems can be more cost-effective due to lower installation and maintenance costs, and lower refill costs compared to gas systems.
Environmentally friendly: They use potable water and can be more environmentally friendly than some other suppression methods.
Bespoke Water Treatment Technologies Used
Depending on the source of water – which could be a bore hole, an open river (surface water), treated sewage effluent, sea water or least likely a potable water source – the water treatment technology differs. Also whether a wet evaporative cooling tower is used or a dry Air HEX (Heat Exchanger), the water quality requirements are different.
Bore holes in Slough, UK for example contain ferrous iron and if this is not removed, then the water turns red due to ferric oxide and all downstream filters get clogged.
Mains water in Holland is soft and there is no chlorine in it. So it is pointless to install a softener or an active carbon filter.
RO is normally used to demineralize the water and achieve higher cycles of concentration. But demin water is corrosive and special materials need to be used in the design of the pipes and equipment.
If treated sewage effluent is the available water source, then the design is completely different. Bacteria and TOC become the main culprits to worry about before subsequent water treatment steps.
If sea water is the medium for cooling, then corrosion resistant, expensive materials need to be used.
Softeners are sometimes used for domestic water user to prevent scale and manage legionella.
Experience of Kremesti Environmental Consulting Ltd.
Rami Elias Kremesti, MD of Kremesti Environmental Consulting Ltd, has worked on Data Centre projects in the UK and the EU. Managing water treatment for a data centre is very similar to managing the water treatment needs for the cooling systems of a power station which also has high standards for up-time and quality. Rami brings his ten years of experience on power stations to help clients to design water treatment systems for data centres.
Operational know how is also very critical because systems like Reverse Osmosis (RO) skids require careful operational monitoring and interventions when they become scaled or fouled or both.
I have witnessed a data center in Slough that had their Ozone cooling tower water treatment system ripped out because it was installed inside and i.t was leaking and setting off the Ozone alarm. Also, in Slough some boreholes are full of iron so careful pre-treatment is required to remove the Iron otherwise the softeners get poisoned and the RO system gets fouled very quickly
Kremesti Environmental has designed training courses to help designers and operators of water treatment systems on data centres to achieve maximum efficiency and minimal downtime.
Figure 1.: Softeners, Active Carbon Filters, Ozone Dosing Systems, Reverse Osmosis Skid as part of a data centre water treatment project in Holland
Environmental Impact
Data Centers are not environmentally friendly period, despite all the green washing. They consume huge amounts of energy and large amounts of water for cooling. Large amounts of electronic waste are generated at the end of their life-cycle. The European Commission remains the world’s conscience when it comes to developing legislation to protect its citizens from the harmful effects of over digitization such as AI and social media.
A prominent data centre in Slough has 1,385 server cabinets x each consuming about 10 Kw of electrical power = about 14 Mega Watts of electrical power consumption. Cooling capacity is about 7 Mega Watts thermal.
How to Make Data Centres More Sustainable
In November 2025, I visited a big data center in Slough. 7 MW cooling capacity. The place is like a prison and the servers are in cages. A bit depressing to be honest. Water cooling the data servers enters at 25 degrees and leaves at 35 degrees C. I dont know the volume of water but this 10 degrees of heat are released to the atmosphere by cooling towers on the roof of the data center. These precious 7 megawatts of heat can be used for district heating.
Data center heat can be used in district heating networks by capturing and transferring the waste heat generated by servers to heat nearby homes and businesses through a system of insulated pipes. This approach reduces the reliance on fossil fuels for heating, lowers cooling costs for the data center, and can create new revenue streams. Projects in the UK, Ireland, and Finland are already implementing this system, which helps lower carbon emissions and energy costs.
Download The Decarbonizing Your Data Center for Dummies handbook from Hitachi Vintara.
Data Center buildings normally have a large surface area, so harvesting their rain water for process use is a sustainable practice that can reduce fresh water demand. One data center that I visited in Slough in November 2025 does that.
Also installing pigeon nets around the cooling towers reduces the risk of water contamination.
Examples of UK Data Center/District Heating Projects
London: The Old Oak and Park Royal area will use waste heat from nearby data centers to supply over 10,000 homes. Schneider Electric is also involved in a similar project at Queen Mary University of London to heat the campus.
Crawley: Waste heat from a data center near Gatwick Airport will supply heating to homes in Crawley, with an estimated 46 GWh of energy being transferred.
Milton Keynes: Plans are in place to use heat from a new data center to warm Milton Keynes University Hospital and potentially other buildings in the city.
Birmingham: Hemiko is developing a heat network in the Tyseley area to capture heat from data centers.
South Cambridgeshire: A proposal for the Melbourn Energy Superloop includes a solar-powered data center and a district heat network in the area.
Regulatory Frameworks – EU and UK
In the EU, the Energy Efficiency Directive (EED) mandates data centres with 500kW (0.5 MW) or more IT power demand to report energy performance data to a new European database as of September 2024. The EU F-Gas Regulation requires phased reductions in the use of high-global warming potential (GWP) refrigerants starting in 2025. In the UK, data centres are subject to the Climate Change Levy (CCL), with energy-intensive businesses using Climate Change Agreements (CCAs) for potential reductions. The UK also has the UK GDPR and Data Protection Act 2018 for data privacy needless to mention.
Conclusion:
To maximise value for investment in a Data Centre project, an efficient water treatment design team is required to begin with. To minimise cost overruns, you need a consultant to over see the project. This is where Kremesti Environmental Consulting Ltd can help. After the system comes into operations, you need an expert water treatment operations team to keep things running smoothly and this requires expert training.
A Look Into the Future
As the AI bubble starts to burst or mildly put, to deflate, the demand for data centres will plateau. The social media craze will die down slowly as people realise the falseness and harm of it all and slowly but surely, people will start to prefer to be off line and to be engaged in more meaningful activities. ChatGPT is already becoming boring and people using it even more so. There is no AI replacement for the intelligent, gentle, kind human touch and connection…. or time spent in Wild Nature in contemplation of the beauty of life. The Machine cannot replace the beauty of the human spirit because the Machine has so Soul…
Rami Elias Kremesti M.Sc., CSci, CEnv, CWEM
About the Author:
Rami Elias Kremesti is a chemist by trade and philosopher at heart. He holds an M.Sc. in chemistry from the USA and has been working in the water and waste water treatment field for over 20 years. He has published several books on Rumi poetry, aesthetics and the beautiful as well as Judaism.
Rami is chartered with CIWEM in the UK as well as the UK Science Council and UK Society for the Environment.
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Rami Elias Kremesti Portrait