Domestic Civil Defence -
Sewage Disposal

Human life produces human sewage and dirty water in quantities that increase yearly. Generally, modern sewage systems can safely remove this by gravity flow down from houses to sewage works. Unfortunately, low-lying areas can rely upon pumps to move sewage up to sewage works, so a power failure may lead to overflowing sewage flooding streets. Overloaded sewers during a flood are a dangerous source of harmful bacteria, so there, too, a hazard can exist. A further problem has been that people evacuated to Rest Centres may overload those services which are available, making it necessary to improvise some kind of sewage disposal. In this section, the writer will show possible methods for safe disposal of both dirty water and sewage in case of breakdowns in this vital service.

It should be pointed out that most municipal and private sewage disposal services can be relied upon to work, as long as there is a minimum flow of water - and any pumps in the system have power.

The problems presented by sewage are as follows :-

• Spread of water-borne diseases such as diarrhoea, dysentery, typhoid, Weil's Disease and cryptosporidiosis.
• Risk of creating a breeding ground for flies, rats and other vermin.
• Contamination of drinking and washing water supplies.
• Risk of food supplies becoming contaminated directly or by vermin with sewage bacteria.
• Production of sewer gases that can be poisonous or which may cause fire risks.
• Severe effects on morale.
• Risks to pets and livestock.
• Contamination of land by incorrect disposal.

Crisis Disposal of Sewage :

To look at the problem in more detail, there are three main kinds of effluent :-

• 'Grey' water produced by people washing themselves, their clothes and keeping their living areas clean. 42 to 79% of household graywater comes from the bath and shower, 5% to 23% from laundry facilities, and 5% to 6% from the bathroom sink
• 'Grey' water from 'Kitchen' effluent, (10% to 17% of grey water) from the kitchen sink or dishwasher, consisting of cold or hot greasy water containing scraps or dissolved foods, produced preparing food and washing kitchen utensils.
• Faecal matter and urine (so-called raw 'black' sewage) - 38 to 45% of all household water use, if flush toilets are used. This can be hazardous if allowed to be colonised by vermin or (more rarely) if it comes from people carrying infectious diseases. Pathogens are present mainly in the faecal matter, but can be destroyed by chemical sterilisation or thermophilic composting. The urine is non-pathogenic and a source of useful nitrogenous fertiliser.

The solution to this headache for the householder is as follows :-

• Provision of the means to keep clean i.e. washing facilities :
  In the section on Water, there is reference to the importance of supplies for washing. As a general rule, if a fire is burning, the heat can at the least be used to heat or boil water for washing. Where there is a shortage of water, then dilute Milton or Dettol solutions can be used to help keep hands clean.
• Enforcement of public health measures :
  In brief, this means never handling food with unwashed hands and keeping food in a safe and secure manner away from contamination by vermin or chemicals. In kitchens, it also means rigid division between Preparation, Cooking, Serving, Eating and Washing areas.
• Reduction of waste volumes :
  This is almost automatic - water shortages leading to use of showers rather than baths, food preparation using bowls of water rather than free-running sinks, washing up by the 'Three Bowls' system of Wash, Rinse and Sterilisation. The disposal of sewage by composting or burial is probably the most radical matter.
• Disposal of Grey Water :
  This has two stages :-
  1. Pre-treatment of 'grey' water and kitchen effluent (removal of solids and grease) :
     At its simplest, this can be filtering wash water through a sieve into a small container (e. plastic bowl or biscuit tin) of shredded card, dry grass or fibre, to catch food particles and grease. Punch holes in the base to let the water trickle out into another container. Burn or bury the contents of the sieve and the container filling once a day and replace with fresh. Alternatively, bury the filling inside your compost bin with sawdust or more fibre, if it is an enclosed type.
  2. Disposal of filtered water to drain or soakaway ~:
     Where land is available, the filtered water can be run into covered soakaway pits of graded rubble or disposed of in loosened clay soil. Where land is not available, the waste water may need to be batch-chlorinated or treated with lime to remove or inactivate wastes before disposal to drains. The household-sized Strainer, Grease Trap Filter and Soakaway is suitable where there is a good loose sandy clay subsoil.
• Reduction of 'black' sewage volume (urinals plus chemical, dry or earth closets) :
  • Chemical 'Porta Potti' and Elsan bucket closets : These use chemicals such as phenol to sterilise waste but in the process may release odours and in any case need to be disposed of. Capacity 2 to 4 days.
  • Dry closets : These use plastic bags and sterilising agents to inactivate and contain waste in small amounts that can be land-filled. Capacity up to a fortnight but expensive and can generate sewer gases. Although advocated by the old Home Office 'Protect and Survive' manual and Cresson Kearney's 'Nuclear War Survival Skills' it is NOT RECOMMENDED.
  • Earth and Sawdust closets : These absorb and cover the waste in about twice the volume of sawdust, shredded fibre, moss, peat, treated clay or earth, for frequent removal for burial and decomposition. A typical and proven sawdust toilet design is the Jenkins Sawdust Toilet,. This uses fibrous material such as sawdust, peat, lawnmowings, etc., to cover each deposit of waste. The emptied bucket is then composted amongst more fibrous material and domestic compostable rubbish. Capacity : With a suitable compost bin and a source of absorbtion material, infinite.
  • Urine Disposal as Compost Activator : Urine can be gathered and treated by absorbtion into fibrous material, a form of composting pioneered by the Centre for Alternative Technology. The writer has used a hay bale there as a remarkably efficient urinal, which decomposes over a year. It is suggested that the soil beneath the bale is loosened to allow access by soil organisms and aid decomposition, Restricting the dry toilet to the modest amounts of urine done whilst defecating solids, one can reduce the general waste volume. The design for a Simple Composting Urinal is under test. Note that it would be big enough for a family, used directly or indirectly through chamberpots.
  • Disposal of wastes by burial or composting :
    The contents of earth closets have been disposed of by composting but this needs rat-proof compost bins and ample dry vegetation or shredded paper to be composted by the ammonia residues in the sewage. The most effective solution other than composting is shallow burial under turf and clay soil of the contents of the earth closets. As a rough guide, restrict burial to one bucketful of sewage/soil mix per ten square feet (one square metre).

  A Personal Experiment - Urine Activated Compost :

  The writer has used urine for the past fourteen years as an effective composting additive. At no time have there been any vermin problems. The trick is to lay a nitrogen trap of woody fibre (e.g. sawdust, shredded twigs, shredded corrugated cardboard or shredded paper) at the base of the compost container to catch any urine leachate. Start the compost on this with a few spadefuls of earth or the previous compost, mixed in with more 'brown' and 'green' material. Continue with layers or mixes of 'brown' and 'green', wetted with urine and water from a collecting bucket for compostings. As the sawdust, cardboard or paper, takes up to 100 units of nitrogen to rot, as against the 1 unit for grass, it is remarkably effective at soaking up both the moisture and the chemical content. Most important of all, the smell is minimal and fly problems non-existent. However, it is a good idea to encourage oxygenation by mixing plant stems, shredded wood (e.g. from chainsawing firewood) or twigs, with such pulpy items as paper and cardboard.

  After careful thought, the writer recommends the following three layouts. :-
  Grey Water : --> Strainer (wastes to compost) --> Grease Trap (wastes to incineration or burial) --> Stone or gravel Soakaway in clay or loam soil.
  Black Sewage : --> Earth or Sawdust Toilet --> Shallow Burial with fibre or container composting.
  Urine : --> Buried Fibre-Bed (compostable soakaway) or container composting.

  Technical Aspects of Human Sewage Burial :

  Going by the professional practice of shallow burial of sewage sludge, no more than 80 kilos of waste should be disposed of by burial in each square metre each year. The writer would suggest limiting burial to no more than one 2-gallon (9 litre) bucket of sewage and dry soil, treated clay or sawdust mix per square metre, less if possible. The soil should not be dug over for at least a year and is safest left under grass.
  If German Mound Gardening is practiced, then a deep core of broken leaves, straw and other fibre, can absorb rather more sewage, as the fibre will absorb all the ammonia and nitrogen. However, drainage is critical; a clay soil with a high groundwater level cannot absorb much sewage without becoming 'sewage sour'.
  However, there are arguments about land disposal of even treated sewage sludge, though these arguments centre more on industrial and medical toxins rather than on human sewage itself. That suggests a better policy would be separate disposal arrangements for human sewage and industrial/medical liquid wastes. The best commentary is on the Jenkins Humanure Handbook website.

  Community Action in Sewage Disposal :

  Towns and villages may find it necessary to re-introduce the nightly collection of waste from buckets, transferring it to a tank of some kind for later disposal at a sewage works or for land burial on farmland. This will need negotiation by someone with official recognition and must not risk later escape of sewage into watercourses. Managed properly, the process can enhance farmland fertility, returning phosphates, nitrates, potash and other nutrients to the soil.

  A town-based household might have to take waste-buckets to some kind of designated burying site or contained composting unit. Incineration may have to be well clear of residential housing. Waste ground (generally former industrial sites) could benefit from composting or burial of wastes, as long as this is not over-done; the worst examples of sewage disposal to land are abuses of what should be a limited application. Composting sewage sludge with a loose fibre is certainly the most effective treatment system before disposal to grassland for burial.

  The Babycare Nightmare : Disposal of 'Disposable' Nappies :

  Disposable Nappies are NOT Disposable, but are a Landfill Hazard
  Appallingly, Australian statistics indicate that 5% of all refuse consists of these sewage-contaminated plastic disasters. These heavily-advertised convenience items represent a sewage time-bomb in any landfill. The best advice in a crisis is DO NOT USE DISPOSABLE PLASTIC NAPPIES. They do not rot underground and the plastic makes them dangerous to incinerate in a bonfire. However inconvenient, consider Terry-toweling nappies with some kind of soft fibre absorbent pad. The best is dried Sphagnum Moss, which is mildly bactericidal, very soft and compostable. The writer discovered that this was used up to the 1900s by Highlands mothers to deal with the three problems of toilet paper, sanitary towels and disposable nappy liner.

Links :
(1) The Humanure Handbook : Copyright 1999, Joseph C. Jenkins. The most detailed online book on composting human waste on the Internet. Based on over 20 years of experience. A must for serious recycling of domestic household waste.
(2) CITA Manorve dry toilet : Mexican site on the theory behind double-vault dry alkaline desiccating toilets.
(3) Some variations on the original Multrum Clivus composting toilet. :

• Nature-Loo.com Dry Composting Toilets
• Cotuit Dry Toilets
• Eco Toilets
• Separett.Com (PDF File)
• Natsol Compus Toilets