So let’s assume that we want clean water leaving our home or business. That’s pretty much a given.
Within that context we need a sewage or sanitation system that works well, but we also want to go
further. The two main steps beyond conventional sewage options are zero energy inputs and
additional benefits for the environment in terms of biodiversity or materials outputs.
In order of preference, here are five places to start:
The first obvious place to start is dry compost toilet systems. These do not use any water; in this
context select a system that also avoids high energy inputs; and provide additional yields of rich
humanure compost to build rich soil and provide an amazing habitat for much beleaguered soil
biodiversity. For urine diverting models they will also provide urine as a separate yield as a fertiliser
source. Lots of plusses. By far and away the most eco-friendly sanitation option going, but
admittedly not necessarily for every home or business. Don’t buy or build one on the strength of a
single article or blog post. Use one yourself before you commit to the maintenance needed and be
sure that your family, staff, guests etc., are on board with the decision.
( https://dryloos.ie/ and https://www.toiletrevolution.com/ )
Choice two on our list is to use source separation technology to remove the urine at the point of the
toilet bowl. “Yellow water” flows to a liquid fertiliser storage tank for removal on local agricultural
land while the “brown water” flows to the next stage of treatment in one of the options below as per
standard “black water” from an ordinary toilet. For faecal solids, wet composting systems can
handle black water or brown water inputs and provide separation via a woodchip filter system or a
Swedish Aquatron faecal separator unit. The finished compost will have same benefits as a dry
compost system when matured and in the soil, but at no noticeable inconvenience of aesthetics to
the user in the bathroom.
Next we’re looking at planted systems that generate a yield. Thus willow planted percolation areas
and zero discharge willow systems. The former is my preferred option given the lower cost and
lower plastic inputs. Ideally provide effective distribution via a Ribbit Splitter (ribbit.ie) or
Herr Flush Box (herr.ie) unit which both use gravity rather than pumping. The willows mop
up additional nitrates and phosphates to really get the water clean; and the wood can be used as a
firewood source for your home. Comfrey is another option for over-planting your percolation area if
you are in a site with a view that you want to keep or a tighter space where willows would be overly
dominant visually. See our post Willows-are-a-win-win. Note that modifications are needed (see our post Willow-planted-percolation-areas) to prevent pipe blockages for either willows or comfrey.
Beyond these options we’re beginning to look at end-of-pipe systems – both literally and
figuratively. Stick with planted systems though, so that you provide additional biodiversity and habitat benefits. Constructed wetland systems are top of my list here because they are the largest
and thus the most effective at both water filtration and habitat provision. One company supplying constructed wetlands is vesienviro.com. Gravel reed beds are next; either horizontal flow systems or vertical flow systems depending on your site size and conditions ( reedbedsirl.com). Ideally return to your willow planted percolation area after the reed bed or wetland to give you additional uptake of N and P, and a firewood crop.
Each site is different, so consider the full range of systems to suite your particular needs. These may
include a conventional septic tank, standard mechanical aeration systems or proprietary filter
systems. Note that of these septic tanks and percolation areas – on suitable soils – will work well on
zero energy inputs for most pollutants bar nitrates. Next, filter systems will only draw power when
there is liquid to pump, putting them ahead of 24/7 aeration systems on the energy input stakes.
Always consider that a willow planted percolation area at the final stage will mop up carbon as it
grows, helping to offset the CO 2 output of your electrical system.
Note that the above don’t necessarily take into account EPA code compliance. Every system is site-specific. Other articles on this website may help with this issue and this specific topic is covered in detail in Septic Tank Options and Alternatives which is available on our bookshop page.