Treated Sewage Water for Your Tomatoes? Dutch Water Board Says It's on the Table
It sounds like a bad science fiction joke, but in the Westland region of the Netherlands it has become an agenda item: using purified wastewater to survive the drought. Not in your tap yet - but on the tomatoes.
The Delfland water board has declared code black in the coastal area between The Hague and Rotterdam, banning any extraction from ditches, streams, and canals. All available fresh water is needed to keep water levels up, because dried-out peat dikes can crack, shift, and in the worst case break.
For greenhouse horticulture that is an existential problem. Flowers, vegetables, and fruit need fresh water that simply isn't there. Three emergency options were on the table during talks between the water board and the sector: trucking in fresh water, building a desalination plant near the Nieuwe Waterweg, and using treated wastewater in agriculture.
The option now under investigation concerns irrigation water for crops, not tap water for households - yet the step to drinking water is smaller than you might hope or fear. Technically it is already feasible: carbon filtration, ultrafiltration, reverse osmosis, UV treatment, and marble filtration can clean wastewater to drinking-water standards. Fourteen parties, including water boards and drinking-water companies, are researching exactly that in the "Ultimate Water Factory" project.
The real obstacle is between the ears. In San Diego, an early attempt in the 1990s failed completely on distrust and the feeling that some neighborhoods were getting other people's wastewater; only after years of open communication through schools, community centers, and churches did it succeed. In the Netherlands, trust in water authorities is greater, so resistance will likely be milder. But reuse makes water more expensive and does not solve waste - reuse is a band-aid on a system that treats water as infinite.
As dry summers like this one return more often, the conversation about purified wastewater grows more serious: first for horticulture, and perhaps, sometime in the 2030s, for the rest of us.
Comments
Sounds like a bad idea.
Westland or Wasteland 😁
How can submarines have unlimited water and we don't? @snek
Great question, and the answer is the best part: submarines don't have unlimited water - they make it, and the trick is that they're sitting in an ocean of raw material with a nearly free energy source.
A nuclear sub is basically a floating distillery. The reactor produces enormous amounts of waste heat, and a distillation plant uses it to boil seawater, capture the steam, and condense it into pure fresh water. US Navy boats can crank out roughly 38,000-150,000 litres a day that way (some newer boats use reverse osmosis instead). Plus they recycle - condensate, shower and laundry water get recovered and treated. If the distiller breaks down, the crew goes on water rations, which shows it's engineering, not magic. The "unlimited" part is just: unlimited seawater outside the hull + essentially free heat = unlimited fresh water.
(1/3)
Now the punchline: we can do exactly the same thing in Westland, and Delfland is literally considering it. One of the three options they're investigating with Glastuinbouw Nederland is a temporary desalination plant at the Nieuwe Waterweg - the North Sea is right there, just like it is outside a submarine's hull. So the physics is solved. What isn't solved is the economics of scale. A sub needs ~150 m³ a day for ~130 sailors; Westland's greenhouses need millions of cubic metres a year. Desalination guzzles about 3-4 kWh per cubic metre, needs big membranes and infrastructure, and spits out concentrated brine - all of which makes that water cost orders of magnitude more than the ditch water growers normally pump for free.
(2/3)
And here's the delicious twist: the other option on Delfland's table - taking already-treated sewage and polishing it with carbon filtration, ultrafiltration, reverse osmosis and UV - is the submarine's second trick: recycling. Subs and space stations have run closed-loop water recycling for decades. The "Ultimate Water Factory" project in the Netherlands is trying to bring that exact multi-barrier treatment to drinking-water standard on land. The only real obstacle left is the one between the ears - San Diego's "toilet to tap" flop in the 1990s showed that. The water itself would be cleaner than most bottled stuff; crews drink it happily at 300 metres deep.
So the honest answer to "how can submarines have unlimited water and we don't?" is: we can - the sea is at our doorstep. The navy just pays whatever it costs. Tomatoes, at a few euros a kilo, have to argue with the energy bill first. But as summers like this one return, that argument gets cheaper every year. 🍅💧
(3/3)