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Why recycle your bathroom greywater?

Before I launch into the design discussion it is necessary to explain what the definition of bathroom greywater is and why one may need to recycle the stuff.  Bathroom greywater as we define it is water that comes from:

  • Showers (the biggest source!) and baths
  • Laundry
  • Bathroom sinks or lavatories

There may be other greywater sources in your particular building, but the ones above pretty much cover it.  Greywater can be used technically for any end use depending on treatment regimen.  Typically, greywater is treated to various levels adequate for reuse in non-potable  uses like toilet flushing and laundry indoors or irrigation and cooling tower make up outdoors.  The treatment regimen is critical to determining the range of application even for these non-potable uses.

Greywater recycling is a viable way to manage water due to evolving technologies like AQUALOOP and the need to rethink 20th century water supply and management philosophies.  With aquifer and surface water depletion from ever increasing demand, we can no longer assume unlimited water supply from nature.  On the other side, we have an ever increasing load on our crumbling water treatment infrastructure.  Greywater recycling helps reduce demand for municipal water from wells and reservoirs and also reduces the load on large scale wastewater treatment plants.

An AQUALOOP greywater treatment system can reduce  household water demand by up to  40%, which is a huge number.  Combined with rainwater collection, use of municipal or well water can be eliminated altogether in many cases.

How much greywater is there:

This quick estimate may be around 37% of the total water consumption is bathroom greywater generated per person on average in a typical residence. We assume standard low flow fixtures and a reasonable amount of conservation and awareness. The actual amount of greywater generated will of course vary for specific situations.  Some people take longer and more frequent showers than others.  Some are actually at home more than others.  

Treated Greywater Uses:

Unlike many other greywater technologies which do a little filtration only, the AQUALOOP  process meets NSF 350 and BS 8250-2:2011 water quality standards and is thus suitable for use indoors and can be stored for extended periods.  With BOD below 5 PPM and coliforms below 2 CFU, the water can be used for any non-potable application including spray irrigation, toilet flushing, laundry, and cooling tower make up (for commercial scale buildings)

The treated bathroom greywater each person generates per year may be used for:

Toilet flushing:   The demand is around 18% of the total household water consumption, according to Watercare, Auckland.

Laundry:  It is quite easy to use treated bathroom greywater from the AQUALOOP for the cold water in laundry.  

Irrigation:  Typically, irrigation will use any water that is available.  This can be done easily by simply sending excess treated greywater to your rainwater tank.  You do have a rainwater tank don’t you??!!

Other uses may include vehicle washing, cooling tower make up, and various process waters.  

See our other blog post which shows that fresh water consumption can be reduced using these system and how rainwater could meet that demand even with very low rainfall.

Bottom Line: 

We figure AQUALOOP bathroom greywater recycling can reduce household municipal or well water consumption by up to 40%.  This goes a long way toward being water independent and alleviating water stress in drought stricken areas.  This can translate into hundreds and in some places thousands of dollars saved on water bills over the course of a year. 

For households that rely on limited water supply (rainwater, wells, etc.) it will save on costly top up by water tankers during summer time or drought periods. It also means that your septic tank will require less maintenance.

For commercial scale, the ROI’s could be much higher due to economies of scale.  It is not unusual to see ROI with payback in less than 5 years.

Please let us know what you think and any questions or challenge points you may have.