Bill & Melinda Gates Foundation

We Have Better Things to do with Clean Water Than Flush it Down the Toilet

March 22, 2013

In 1993 the United Nations General Assembly declared 22 March as World Day for Water, and people have embraced the entire week in an attempt to shine the spotlight on the global water issues.

In my line of work I often get asked, if here in America we enjoy the fruits of a sewer and wastewater treatment plant system why does our Water, Sanitation and Hygiene group not support sewer systems in developing countries?

There could be situations where a sewer system might be the best option. But, when you look at cities in developing countries, these systems just don't make any sense.

I could talk about the up-keep cost of sewer systems – where I live in King County, Washington, we spend about $300 million a year just keeping our sewer system and treatment plants maintained and running. I could also talk about ongoing costs of expanding the network as urban centers develop and grow. Or, I could talk about the challenges and costs associated with laying pipes in a slum setting. Seeing that they’re typically informal settlements, who would be responsible for absorbing those costs? However, in honor of World Water Day, let’s just talk about water and sanitation.

Sewer systems, as we in the developed world know them, really function by their ability to move human waste. That means we need not only to flush our poop and pee down the toilet, but we also need enough water to push it all the way to treatment plants.

We each, on average, poop about 25 pounds of dry fecal matter every year. That means if you had the desire (not recommended) to collect all of your poop for 12 months and dry it out completely, it would weigh roughly 25 pounds and fit into a small carry-on suitcase. In our current sewer-based system, we then use 4757 gallons  of drinking water (yes, drinking water), per person every year to flush that poop down the toilet (it drops to about 1850 gallons a year if you have a low-flush toilet). For reference, when you have a bath, you use about 35 gallons.

BUT WAIT! That’s not all!! To actually move the poop from our toilets all the way to waste water treatment plants, we need additional water from our dishwashers, showers, washing machines…and the list goes on to keep things moving. If we don’t have enough water and the poop doesn’t get pushed to the treatment plant fast enough, bad things can happen in our sewers.

The World Health Organization recommends a minimum of 5 gallons of water per person per day for everything: washing, cooking, and drinking. Unfortunately, we know very well that a WHO recommendation does not necessarily translate into things actually happening. If you do the math, 5 gallons of water per day comes to around 1,850 gallons per year. The same amount of water that we lucky folks would use just to flush our poop, if we have low flush toilets.

The average person in the United States uses around 80-100 gallons of drinking water EVERY DAY and most of that ends up in the sewer to keep the sewer system functioning properly.

So, we can look at construction costs of sewers, we can ask how much it would cost to keep the sewer in operation, we can study how we would lay sewer lines in developing country urban slums, but at the most fundamental level, people living in a developing country slum have a lot of better things to do with their 5 gallons a day of water than flush it down a toilet.

On this World Water Day, I encourage you to learn more about how rethinking sanitation systems leads not only to healthier communities, but how it would free-up clean water to be used where it is needed most - for families around the world to drink, cook, and bathe safely.

Learn more about the Gates Foundation’s approach to water, sanitation & hygiene. Do find out how you can get involved, visit WaterAid here and follow #sanitation on Twitter.

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