Rainwater Harvesting Systems for High Tunnels

Introduction

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Three specialty crop farms in eastern Kansas constructed rainwater harvesting systems for high tunnels to help respond to increasingly erratic rainfall and temperature patterns. The project documented the materials needed, the system costs, how much water can be saved, and lessons learned for sharing.

Participants

• KC Farm School at Gibbs Road, Wyandotte County, KS, Alicia Ellingsworth and David Dods
• Herdsman House Farm, Miami County, KS, Sharon Autry
• Moose Paw Farm, Miami County, KS, Jacob Chapman

Precipitation / Challenge to be Addressed

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High tunnels require irrigation within them, and the rain that falls on the roof can be a source for the water if it can be collected in a cost-effective manner and the water available during wet seasons can be stored for dry periods. To plan this project, 50 years of local weather data were reviewed. The historical temperatures and rainfall in Kansas City, MO show how weather patterns are changing and making conditions more challenging for growers.

Average Monthly Temperature (^oF): 1970s vs. 2020s

Years	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Annual
Change, 1970s - 2020s	2.4	-1.6	7.3	1.6	-0.5	1.4	0.5	-1.1	3.7	5.9	3.7	4.0	2.2

Average Monthly Precipitation (in.): 1970s vs. 2020s

Years	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Annual
Change, 1970s - 2020s	0.6	-0.2	0.1	0.2	-0.6	1.1	2.3	-0.9	-3.7	-1.4	0.6	0.1	-1.7

Since the 1970s, in the Kansas City area, fall and winter have become much warmer and fall has become much drier. In 2025, the KC Farm School recorded only 2.2 inches of rain from August through October.

These patterns are the basis for planning the rainwater harvesting systems. The goal is to catch and store extra rainwater through early summer to store for use during the dry fall period. A spreadsheet was developed to size the water storage tank or pond from the monthly rainfall and the water used for irrigation.

See “Contact for More Information” at the end of this report to request a copy of the spreadsheet.

System Components

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The systems at KC Farm School and Herdsman House Farm included the following:

• 5” K style gutters
• PVC pipes
• 275-gal IBC ((intermediate bulk container) totes for storage
• 1.25" 1-hp 220v pump
• Solar panels
• 8 - 55Ah 12v batteries

The tunnel at Herdsman House farm is 30 ft x 72 ft, with 5 ft high wood hips and roll up sides. It uses 6 IBC totes for water storage (1,650 gal).

The tunnel at KC Farm School is 20 ft x 72 ft, with 5 ft high steel hips and drop-down sides. It uses 4 IBC totes for water storage (1,100 gal).

Annual Water Savings

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The annual amount of irrigation water that can be provided from rainwater at each farm is estimated at: 38,000 gal for Moose Paw, 29,000 gal for Herdsman House and 18,000 gal for KC Farm School.

Those amounts are a function of the size of each storage system, the size of the high tunnel, and how much irrigation water is used each year. Moose Paw Farm with the pond (instead of IBC totes) can store much more water during rainy months.

Costs

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Material costs (2025) for each farm are below. These do not include labor or equipment rental.

• Moose Paw Farm: $4,800
• Herdsman House Farm: $7,100
• KC Farm School: $6,500

The major costs at Herdsman House and KC Farm School were the solar panels, batteries, and pumps. Moose Paw Farm had an existing pump so it did not need those components. The major cost at Moose Paw Farm was the pond liner.

Challenges / Lessons Learned

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• Carefully plan the system design and layout. Hip materials (wood, metal) and pulleys for drop down sides affect how gutters are installed. Hip heights affect pipe clearances to the storage tanks.
• Storage volume. If space allows, a pond provides much greater storage volume than the tanks. Ponds will grow algae, attract wildlife, and require safety considerations in design, so plan accordingly.
• Algae management. The clear tanks grew algae. That can be prevented by wrapping or painting the tanks to keep out light and adding first flush diverters to the gutters to limit sediment and debris.
• Pumps. The solar pumps used in this project were indoor pumps that required winterizing.
• Water Treatment. A sediment filter plus drip irrigation is used at each of these systems. The water would need to be further treated and disinfected for overhead irrigation on leaf crops.

Contact for More Information

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Alicia Ellingsworth, KC Farm School at Gibbs Road, Kansas City, KS, alicia@kcfarmschool.org

This project was funded by a regional Sustainable Agriculture Research and Education (SARE) grant. For more information about SARE grant opportunities across the country, please visit https://www.sare.org/grants/.

Thank you to David Dods for preparing this case study.