A Bell and Paton greenhouse tunnel on Johan Gerber's property in Knysna.
When we design and supply greenhouse tunnels, we think about the obvious jobs: keeping frost off seedlings, extending the growing season, and protecting crops from wind and pests. But every so often, one of our customers finds a use for their tunnel that we never planned for — and it teaches us something new about what these structures can really do.
That's exactly what happened with Johan Gerber, a Bell and Paton customer based in Knysna.
A Region Under Pressure
Knysna, like much of the Garden Route, has faced ongoing water restrictions in recent years. For home growers and small-scale farmers, this creates a real dilemma: how do you keep a productive tunnel full of thirsty crops alive when municipal water is limited and every litre counts?
Rather than scaling back his growing operation, Johan turned his tunnels into part of the solution.
Turning the Tunnel Itself Into a Water Source
Every tunnel naturally generates condensation. Warm, moist air rises off the soil and plants during the day, meets the cooler plastic skin of the tunnel, and condenses into water droplets. On most tunnels, that moisture simply runs down the inside of the cover and back into the soil. Johan realised that with a small modification, that same moisture — along with rainwater running off the structure — could be captured and reused instead of being left to chance.
Rows of Bell and Paton tunnels at Johan's Knysna site.
Working with the mesh ventilation panels along the sides of his tunnels, Johan set up a simple system of channels and 20-litre buckets positioned along the base of each tunnel wall. Condensation forming on the inside of the cover, along with rain that collects on the tunnel roof and runs off the sides, is directed down and funnelled straight into the waiting buckets below.
A close-up of the mesh vent panel and collection point.
It's a beautifully simple idea: no pumps, no electricity, no complicated plumbing. Just gravity, careful positioning, and an understanding of how his tunnels already behave in different weather.
Enough Water for Every Crop
The results speak for themselves. Lined up along the pathways between his tunnels, rows of labelled buckets — clearly marked for different crop trials and beds — collect enough water to irrigate everything growing inside.
Buckets collecting water between the tunnel rows, labelled by bed and crop.
By harvesting water that would otherwise be wasted, Johan has managed to keep his tunnels fully productive despite the restrictions affecting the wider region — a genuinely self-sufficient system built entirely around the structure he already owned.
Why This Matters for Bell and Paton Growers
Johan's setup is a great reminder that a greenhouse tunnel is more than just a season-extender or a windbreak. With 30 years of experience supplying tunnels, hydroponic systems, and garden infrastructure across South Africa, we're constantly hearing from customers who adapt their tunnels to solve problems specific to their own conditions — whether that's water scarcity, extreme heat, or unusual crop combinations.
If you're growing in a water-restricted area, a few of the principles behind Johan's system are worth considering for your own tunnel:
- Position collection points at natural low spots where condensation and rain runoff already gather along the tunnel base.
- Use the ventilation mesh panels as a guide for water flow — they're often where moisture concentrates first.
- Label your containers by bed or crop, as Johan does, so you can track how much water each area is actually receiving.
- Start small and observe — Johan's system evolved over time as he learned how his particular tunnels behaved in Knysna's climate.
Got a Clever Use for Your Tunnel?
We love hearing how our customers put their Bell and Paton tunnels, hydroponic systems, and garden structures to work in ways we hadn't imagined. If you've adapted your setup — for water harvesting, unusual crops, or anything else — we'd love to feature your story too.
Thank you to Johan Gerber for sharing his water harvesting system with us. It's innovative, resourceful growing like this that keeps teaching us just how versatile a simple tunnel can be.