The benefits of capturing and reusing greenhouse drain water

Introduction  

Karmajeet Singh and Vikramjit Momi are landholders who produce blueberry, rubus and greenhouse cucumbers on their property near Glenreagh, NSW. 

Challenges 

Potential for excess nutrients from greenhouse vegetables running off into bordering creeks.  

Generating drain water is a necessary practice when growing greenhouse vegetables in substrate to prevent salt build up. As Bagawa Creek and the Orara River border the property, the nutrient rich drain water needed to be managed to prevent the possibility of it entering the waterway.   

Initially, the drain water was captured in a plastic lined pit that was used on a nearby vegetable patch and grassed area. However, it was not large enough to handle additional storm water and could not be recirculated. 

Solution 

“We wanted to make sure the drain wastewater wasn’t going to enter the nearby creek, and now with recycling we don’t have to add fertiliser for our older blueberries for 8 months of the year.”  
- Karmajeet Singh 

With support from Local Land Services, Karmajeet and Vikramjit recieved a Clean Coastal Catchments On Farm Works Grant in 2023 to upgrade their irrigation system and capture then reuse their greenhouse cucumber drain water.   

Grant funding was used to:  

• engage a local irrigation company to install a capture and re-use system
• install a firefighting pump
• install a 4000L sump
• lay 800m of polypipe to a 25000L holding tank linked to the fertigation system. 

Outcomes  

The Clean Coastal Catchments grant supported by LLS has resulted in:

• significant reduction to the risk of runoff
• recycling of the waste-water
• savings for the business.  

The sump tank captures all greenhouse cucumber drain water, which prevents it from entering nearby Bagawa Creek and Orara River. Instead, nutrient-rich waste-water can be directly used on the nearby vegetable patch (which is soil-based).  The excess is then transferred to the holding tank near the main irrigation shed with a float valve in the sump to trigger the transfer.  

The excess water in the holding tank is then blended with dam water to a target Electrical Conductivity (EC) value for use on the blueberries. For 8 months of the year, Karmajeet and Vikramjit don’t use any additional fertiliser (applying only in the reproductive period).   

Karmajeet estimates he saves $45,000 annually in fertiliser costs across 3.2 hectares. 

Ongoing Work  

Karmajeet and Vikramjit are always looking to improve the sustainability and productivity of their business. Drain water testing has commenced to ensure no recipe modifications for blueberries are required.   

In addition, the firefighting pump and battery used to circulate the wastewater sometimes does not run long enough to recharge. Whilst a small issue, in the future Karmajeet and Vikramjit would like to replace the battery with an electric pump powered by solar panels. 

Funding and partnerships  

The Clean Coastal Catchment project is funded under the NSW Government’s Marine Estate Management Strategy. The ten-year strategy was developed by the NSW Marine Estate Management Authority to coordinate the management of the Marine Estate.