Bill Gates, pit latrines and removing waste safely

October 1st, 2020

“It’s magical that there is a sewer system…”

Healthabitat (HH) couldn’t agree more. A functional toilet that safely removes waste is a crucial part of Health Hardware. Have a look at this video where Bill Gates outlines the key criteria of a functional toilet.

Bill Gates brings up some very important points in this video;

  • For the poorest 2.5 Billion, a western-style flushing toilet is unaffordable
  • Pit latrines do not process waste, they do not remove harm causing pathogens and they smell
  • Getting rid of waste is key to human health

Unfortunately, these key criteria are not met in many toilets that are built by charities around the world. Whilst these toilets are built with the best intentions, this is not always enough for continued health benefits.

A common solution to toilet construction in developing countries is the pit latrine. They vary from a hole in the ground, deep lined perforated pits or concrete rings dug into the ground. They have some advantages being;

  • Relatively cheap to build,
  • Can be built with a variety of local materials
  • Require a small land area to be built on
  • Does not require water to function

However, they have some significant drawbacks, being;

  • Flies and odours are normally noticeable
  • Low reduction in Biochemical Oxygen Demand (BOD) and pathogens with possible contamination of groundwater
  • Costs to empty may be significant compared to capital costs
  • Sludge requires secondary treatment and/or appropriate discharge
  • No specific reuse of faeces and urine
  • Pits are susceptible to failure/overflowing during floods
  • Stagnant water in pits may promote insect breeding

Some design criteria for a pit latrine – Image from

In Nepal, HH has seen these types of low initial capital toilets used often.

Some non-government organisations give out the raw materials for the pit and then expect the family to find the initiative and the money to build the rest. HH wrote about this in a BIG ISSUE.

HH’s approach to toilets whilst having a higher initial cost has a greatly improved chance of continued health benefits. HH champions that poor people do not deserve poor design. Bill Gates’ call to ‘Reinvent the Toilet’ is a great example of good design to people who need it the most.

HH worked with local mobs to design a septic tank for Bangladesh, seen here under construction. Note the water around the tank. Waterproofing is critical

Until we have ‘re-invented the toilet’ there are existing methods that safely treat waste. In Nepal and Bangladesh HH uses a septic tank to safely treat waste. However, these different conditions require different solutions. A high water table in Bangladesh means all the septic tanks had to be waterproof as to not impact on the quality of the groundwater. In Nepal, farm animals meant a biogas chamber was used in conjunction in some designs to create free, clean-burning fuel from the excess waste.

This video made for HH shows how the septic tank in Nepal works.

We look forward to seeing what comes of ‘re-inventing the toilet’ in tandem with good design for all people with current solutions.