Data centre water consumption

Overview

The ICT sector will grow, with 29.3 billion devices expected online by 2030, up from 18.4 billion in 2018. Data-centre energy consumption regularly receives coverage, but analysis of water consumption is scarce. The paper examines how data centres consume water directly for cooling, in some cases 57% sourced from potable water, and indirectly through the water requirements of non-renewable electricity generation. In the USA, data-centre water consumption is about 1.7 billion litres/day, against total US consumption of 1218 billion litres/day.

Context figures: the US average water intensity of electricity generation in 2015 was 2.18 L/kWh; consumption for hydropower is 16.8 L/kWh, compared with 1.25 L/kWh for thermoelectricity. Digital Realty sourced 64% (2017), 65% (2018) and 57% (2019) of its water from potable supplies. A small 1 MW data centre using traditional evaporative or cooling-tower cooling can use around 25.5 million litres of water per year. Raising chilled-water temperature from the usual 7-10 °C to 18-20 °C can cut expenses by 40%.

WUEsource adds annual source-energy water use to annual site water use and divides by ICT equipment energy; the author recommends that cloud vendors calculate and publish it alongside PUE. Less than a third of data-centre operators track any water metrics, and water conservation is ranked as a low priority. Electricity generation is the largest contributor to a data centre's water footprint but is invisible without metrics like WUEsource. Moving to the cloud is more efficient, but transparency is a major issue: Microsoft and Google produce detailed but aggregate environmental reports, and Amazon publishes almost nothing.

Limits: a perspective with no new measurements; values are collected from published company reports and generic grid water intensities. Industry directions listed include free cooling, higher chilled-water temperatures, recycled water, liquid cooling and siting.

Key points

1. US data-centre water consumption is about 1.7 billion litres/day, compared with total US consumption of 1218 billion litres/day.
2. The US average water intensity of electricity generation in 2015 was 2.18 L/kWh; consumption for hydropower is 16.8 L/kWh, compared with 1.25 L/kWh for thermoelectricity.
3. Digital Realty sourced 64% (2017), 65% (2018) and 57% (2019) of its water from potable supplies.
4. A small 1 MW data centre using traditional evaporative or cooling-tower cooling can use around 25.5 million litres of water per year.
5. Raising chilled-water temperature from the usual 7-10 °C to 18-20 °C can cut expenses by 40%.
6. Less than a third of data-centre operators track any water metrics, and water conservation is ranked as a low priority.
7. WUEsource adds annual source-energy water use to annual site water use and divides by ICT equipment energy; the author recommends cloud vendors publish it alongside PUE.

Using it in design

• In cooling selection, add the roughly 25.5 million litres per year per MW of evaporative cooling water need and the potable share (57-65%) to the siting and water supply decision.
• Evaluate raising chilled-water temperature from 7-10 °C to 18-20 °C and free cooling as both energy and water reduction options (expenses can fall 40%).
• Report WUE and WUEsource (including indirect water from electricity) alongside PUE.

Who should read it

Designers and sustainability managers evaluating data-centre water use, reporting and cooling selection.

Document contents

1. Introduction
2. Direct and indirect water use in data centres
3. Measuring and reporting water consumption: WUE and WUEsource
4. Published hyperscaler figures and grid water intensities
5. Industry directions: free cooling, higher chilled-water temperatures, recycled water, liquid cooling and siting
6. Conclusions

Related standards

• The Green Grid WP35 (WUE)
• ISO/IEC 30134-9

Read the document

Publication details

Authors

David Mytton

Publisher

npj Clean Water (Springer Science and Business Media LLC)

Year

2021

Volume

4

Issue

1

Pages

11

Document language

English

Source type

Scientific

Access

Open licence — downloadable

DOI

10.1038/s41545-021-00101-w

Licence

CC BY 4.0 — share with attribution

Licence evidence

www.nature.com

Citation