From Pecunia Non Olet to Sustainable Sanitation

Even ancient Rome proves that one person’s waste is another’s resource. Emperors have always needed money, and Vespasian (AD 69–79) turned a stinky problem into tax revenue. Public latrines collected gallons of urine rich in ammonia, which tanners and fullers used to soften hides and bleach togas. When his son Titus balked at taxing human waste, Vespasian famously held a coin under his nose: Titus smelled nothing – “money does not stink,” the emperor quipped. The tax on vectigal urinae (urine duty) coined the phrase pecunia non olet (“money doesn’t smell”). It was an early lesson that in a money-driven world, value can come from the foulest sources.

With an environmental twist, this odd chapter has modern resonance. After all, we still flush away mountains of pee and poo: an average person produces about 128 g (4.5 oz) of feces and 1.42 liters (48 oz) of urine daily. Multiply that by today’s ~8 billion people and it adds up fast – on the order of billions of tons of solid waste and trillions of liters (or quads of gallons) of urine each year. All that biology can, in principle, become fertilizer – if we don’t just wash it away with fresh water.

Ancient latrines like these in Ostia supplied Rome’s tanneries and laundries with urine. By taxing it, Vespasian turned this valuable resource into revenue.

But in our water-rich era we tend to flush and forget. Toilets can guzzle 6–7 liters (1.6–1.8 gallons) per flush in modern homes, and even more in older fixtures. With about 5 flushes per household per day, a family easily pours tens of thousands of liters (thousands of gallons) of water per year into the sewer. The Rich Earth Institute points out that Americans alone dump about 1.2 trillion gallons (4.5 trillion liters) of drinking water down the toilet each year. That’s roughly 15,000 liters (4,000 gallons) per person per year just for flushing pee and poop. All that water costs money to treat. In the U.S., for example, the average household now spends about $550 per year on sewer/wastewater services, and rates keep rising. Globally, water utilities and governments pour hundreds of billions into sewage infrastructure – an entire industry built around managing human waste.

Yet sanitation remains a huge challenge. Today about 4.5 billion people lack safely managed sanitation (toilets and treatment), and roughly 80% of the world’s wastewater flows untreated into rivers, lakes or oceans. When human waste isn’t safely disposed, it contaminates water and spreads disease. In reality, 80% of the nitrogen and phosphorus pollution in water comes from untreated human waste. In other words, nutrient-rich pee and poop from farms and cities is largely washing into waterways instead of feeding crops.

Fortunately, there’s a flip side. Human waste is packed with plant nutrients, so treating it as “black gold” rather than trash makes sense for sustainability. In the U.S., for example, it’s estimated that the annual urine output of Americans could replace about 4.1 million metric tons (9 billion lbs) of chemical fertilize. One person’s yearly urine could grow roughly 145 kg (320 lbs) of wheat. Some farming systems already use treated human byproducts: cities make biosolid compost or pellets from sewage sludge (Milorganite® is one well-known example), and manure from farms is a classic fertilizer. Separately, dedicated “urine-diverting” toilets and containers capture fresh pee. Organizations like the Rich Earth Institute show that source-separated urine contains mainly nutrients and almost no heavy metals, making it a safe, potent fertilizer if handled properly.

Modern policies reflect a balance of caution and innovation. In the EU, regulations ensure sewage sludge (treated fecal material) is safe before it’s applied to fields. Some countries encourage recycling nutrients: Sweden, for example, has targets to recover a large portion of phosphorus from wastewater and is piloting urine-collection systems. At the same time, most places require any human waste to be properly treated or composted to kill pathogens. In other words, while the raw stuff might support plant growth, it can’t be directly dumped on veggies without oversight.

The good news is, our concept of “waste” is slowly evolving. Composting toilets, biodigesters, and urine-fertilizer projects are spreading. If we take Vespasian’s lesson seriously, we see that the value in waste isn’t about pride or smell – it’s about resource efficiency. No matter how foul something seems, if it contains nutrients or energy, it can be turned into benefit. In today’s sustainability challenge, even pee and poop can pull their weight. Pecunia non olet indeed – when used wisely, waste does become precious.

What are your thoughts on flushing versus recycling human waste? Share below!

Products (affiliates):

• Sun-Mar Compac Composting Toilet – A popular waterless composting toilet (suitable for tiny homes, cabins, etc.). (Note: Link leads to Amazon.)
• Humanure Handbook by Joseph Jenkins – A classic DIY guide to composting human manure. (Note: Link leads to Amazon.)
• Milorganite Organic Nitrogen Fertilizer, 6-4-0 – Lawn and garden fertilizer made from recycled treated sewage sludge. (Note: Link leads to Amazon.)
• Smart Pot Organic Compost Grow Bags – An organic growing medium for plants (great for a home compost/garden project). (Note: Link leads to Amazon.)