Saving Water (Part 2)

Saving water

Saving water in the business and saving money too

What uses the most water every day in the washroom? – Urinals

We are looking at the cost of water to business which is not insignificant – remember Scottish Water costs 85p per m3.  However, the water companies charge £1.43 to dispose of that same m3.    So the true cost is £2.28 per m3.   So saving water can make help reduce costs.  The truly guilty party in the washroom area, when it comes to wasted water, are Urinals and let me explain.

The Problem

So here is the real trouble maker.  Actually it’s not the Urinals that cause all the problems but the urine that goes into them and a fundamental design flaw.  Unlike a standard toilet which has 3-6 litres of cold water sitting in it when you go to use it, a urinal has 300-500ml of partially diluted urine sitting in the ‘U’ bend.   This creates the airlock which prevents the smells from returning from the stack or sewer.

In a standard (sit down) toilet any urine is immediately diluted in cold water and flushed down a 10 – 15cm waste pipe.  In a Urinal, the warm urine sits in the ‘u’ bend and is washed down a 2 – 2.5cm waste pipe.  Where the liquid in the urinal sits a ‘tide’ mark will form and this organic material is the catalyst that allows the uric acid in the urine to crystalize.   This accelerates as other organic material (chewing gum, hair, phlegm, etc) sticks to this area.  Flushing water doesn’t remove this build-up and can accelerate the problem.  The harder the water the quicker this problem will occur.

So no matter how good your systems are, urinal pipework needs to be cleaned on a regular basis depending on usage and water hardness.  I am sure a mathematician would be able to create a formula to show the two factors and how often a blockage occurs.

The Options

Those of you that haven’t yet:

  1. fallen asleep
  2. been sick
  3. clicked over to look at cats sitting on vacuum cleaners

might be asking – what have the problems listed above got to do with water saving?  Well here’s the thing,  no matter how much water you flush down your urinals the problem will still be there.  And if you are in a hard water area you will actually be making the problem worse.

A programmable valve will drastically reduce water wastage

If you are in a harder water area you will get a double benefit by reducing the water flow into your urinals.  It is a great and easy exercise to work out how much water you are currently using by looking at the size of the cistern and then waiting in the toilets with a watch and to see how often they flush. So a standard cistern flushing every 15 minutes equates to

0.009 x 4 x 24 = 0.864m3 x £2.28 = £1.97 per day = £719 per annum

An easy calculation.  But remember to calculate per cistern NOT per urinal.

The simplest serviced water management system costs around £200 to buy and install per cistern.  (get more info here) By fitting a system and reducing the water flow to every hour (0.009 x 24 x £2.28) would reduce the water costs to £180 per annum and with the water management system installed the annual saving would still be £339 per annum.

With that saving I would be tempted to pay a plumber or washroom company an additional £80 to proactively come in once a year and clean the urinal pipes back to the stack, this is much cheaper than a call out fee.

Waterless Urinals are another alternative and I’ll share some insights in my next article.

If you need any advice or assistance, please do call us on 0844 2499 244 or email today to