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Rainwater Harvesting for Vegetable Gardens

Updated: Sep 14, 2023

In general, most of New Zealand is subject to water restrictions during the hottest summer months.

These restrictions can impact garden care as they can include hosepipe and sprinkler restrictions or complete bans, depending on region and rainfall levels.

Many New Zealanders have invested much time and money in their gardens and vegetable gardens, and wish to ensure that they retain their beauty and productivity during our hottest months.

Domestic rainwater harvesting in both urban and rural environments can allow gardeners to maintain a level of irrigation which supports their gardens and provides the opportunity for homegrown produce to thrive.

Different gardens will have different watering requirements, and therefore the amount of water storage required can vary from garden to garden. Individual properties may also have factors impacting water tank placement, and there are a range of sizes and shapes available to suit most sites.

Dripper irrigation on vegetable garden

Factors Influencing Watering Needs

  1. Climate and Location New Zealand's climate varies from region to region, so understanding your local climate and microclimate is essential. Coastal areas tend to be milder, while inland regions experience greater temperature fluctuations. The North Island generally has more consistent rainfall compared to the South Island. Always take your specific location into account when determining your garden's watering requirements.

  2. Soil Type The type of soil in your garden greatly impacts its water-holding capacity. Sandy soils drain quickly and require more frequent watering, while clayey soils retain water for longer but can become waterlogged. Loamy soils strike a balance and are generally the most forgiving.

  3. Vegetable Types Different vegetables have varying water requirements. Leafy greens like lettuce and spinach need more water than root vegetables like carrots and radishes. Tomatoes, cucumbers, and peppers also tend to be thirstier. Grouping plants with similar water needs together can help you manage your garden more effectively.

  4. Growth Stage The growth stage of your plants influences their water needs. Newly planted seeds and seedlings require consistent moisture to establish their roots, while mature plants may need less frequent but deeper watering to encourage healthy growth and production.

How Much Water Does Your Vegetable Garden Need?

  1. Litres per Square Meter We recommend, as a general guideline, that a vegetable garden will require 5-10ltrs of water per day per square meter (depending on planting and environmental factors, as discussed above).

  2. Timing Matters Water your garden in the early morning or late afternoon to minimize water loss through evaporation. Avoid watering during the hottest part of the day, as this can stress plants and waste water.

  3. Mulching Applying a layer of mulch around your plants helps retain soil moisture, reduces weeds, and regulates soil temperature. Organic mulches like straw or wood chips work well in vegetable gardens.

  4. Drip Irrigation Consider installing a drip irrigation system for efficient and targeted watering. Drip systems deliver water directly to the base of plants, reducing water wastage and minimising the risk of fungal diseases on leaves.

Over the course of the driest 4 months this means that a 10 square meter vegetable garden will require approximately 6,000ltrs of water at 50 ltrs a day (on the low side of our recommendation).

Different Types of Water Storage Tanks

The tanks below are those most suited to smaller scale water harvesting, much larger tanks are available in both plastic and concrete to suit larger scale needs.

Slimline Tanks

These slimline tanks come in 1,000ltr modules which can be joined to create your required storage capacity.

They are well suited to urban environments and provide a smart solution for small spaces.

Urban Tanks

Urban Tanks are super narrow tanks, suiting installation against a wall or fence line. They are perfect for small urban sections and come in three size; 1000ltr, 2000ltr and 3000ltr and in a range of colours to suit most environments.

Small Tanks up to 10,000ltrs Small tanks range from just under 500ltrs to 10,000ltrs and can provide a cost effective option and greater capacity than the slimline and urban tanks. There are a range of options available to suit most requirements.


Watering your vegetable garden during the summer months requires consideration of your local climate, soil type, plant varieties, and growth stages. Rainwater harvesting for vegetable gardens is an excellent option to provide a sustainable water source for hand watering or irrigation.

A range of water tanks are available to suit almost every storage capacity and location requirement. By monitoring soil moisture, practicing efficient irrigation techniques, you can help your garden thrive and produce an abundance of fresh, healthy vegetables all summer long.

At WTS we are happy to visit to discuss your individual requirements for both water harvesting and irrigation, to ensure that you are able to enjoy your own homegrown veggies all year round. Contact Us for further information

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