How To Calculate Office Water Use

Before starting to help the environment by reducing your office water use, you must first establish how much water is being used and where.

Monitoring Office Water Deliveries

The first stage in tackling the current levels of water use within the workplace is to calculate how much water is being used at present. The best way to do this is to create a site water balance.

Based on the basic principle that what goes in must come out, the water balance is a numerical account of where water enters and leaves the office site, and where it is used in the meantime. This office water delivery chart provides office managers with an overview of the key uses of water on their site and helps them assess and control its water use and effluent production.

A carefully prepared water balance is able to help organisations of all shapes and sizes reduce their water use, save money and increase their profits.

Six Stage Programme

The government-funded programme Envirowise, set up to offer businesses advice about reducing their impact on the environment, has devised a six stage procedure to help organisations construct their own water balance. The basic stages comprise of:

• One – obtain commitment of senior management and assess the resources required.
• Two – collect together all appropriate data, such as water bills and meter readings. Ideally these should account for 80% of the water paid for.
• Three – either using a sketch diagram or flow chart, show all the areas and processes that use water. This should include the location of water meters, waste discharge points and any unnecessary water usage such as leaky pipes.
• Four – quantify and record each area of water use and effluent flow in the form of units, and then work out the appropriate costs.
• Five – identify the areas where water savings can be achieved. Use the balance to rank target areas according to volume, potential short payback period and which use high grade water.
• Six – monitor progress by conducting regular reviews and updates.

The full programme is detailed in the Envirowise guide ‘Tracking Water Use To Cut Costs’ and is available as a download from their website. The site also provides a variety of Excel-based monitoring tools for free use.

Office Of Water Use Efficiency Targets

But how do you know how much is an efficient amount of water use and how much is excessive?

The Building Research Establishment (BRE) has set a best practice water consumption target of 4m³ per employee per year. This is only an approximate target and would be expected to increase with larger offices or those with catering facilities.

In order to work out how much water the average employee in your office consumes in a year, you just need to follow this simple formula:

Annual water consumption ÷ number of employees = water consumption per annum

Benchmarking Tools For Water Deliveries

An additional and more precise measure is to use an online benchmarking tool. Such tools allow companies to compare their water consumption with that of others in their sector, thereby helping to gauge their relative performance. Of course this doesn’t mean companies should limit their water saving ambitions to those of the competition, they should just assess whether they are leading the way in the field of water efficiency or trailing behind.