WaterMate : an automatic solar polytunnel watering system

Peace of mind, productive growing, and less time spent watering.

Harvst WaterMate Pro is a solar watering system for polytunnels up to 40 metres squared, using dual zone system for drip irrigation, misting, drippers, sprayers or soak hose.

It’s a solar watering system that needs no mains power : 100% off grid.

The powerful pump means you don’t need a tap or garden hose, so it can run anywhere you have a water tank. If you have a tap, just leave out the pump.

It’s smart, and saves water. It won’t water when the soil is moist, and can water extra when you plants need more. It tracks temperature and coupled with a timed system, delivers just the right amount of water to your plants.

It’s app controlled, and if your polytunnel is within range of a WiFi network, you can manage and monitor from anywhere, and even receive email alerts.

Buy as a complete irrigation kit in a box

Harvst WaterMate is a smart, solar powered automatic watering system designed for polytunnels.

  • Spend less time watering
  • Install anywhere
  • Solar powered
  • Dual zone irrigation
  • Pump from a water tank
  • Environmentally responsive
  • App controlled
  • Manage and monitor remotely
  • Pipes & polytunnel fixings included
  • Sprayers and drippers included
Polytunnel watering system

For larger polytunnels
… up to 12′ x 18′ or 40m2

Solar powered

WaterMate is powered by a built-in battery, charged by a solar panel, which means you can run it anywhere there’s sunshine.

The solar panel just needs to be mounted where it gets the most amount of sun. It’s provided with adjustable brackets which will screw to a timber frame, or to a wall or fence.

The solar panel is approximately 350 x 220 x 18mm in size.

Use a water tank …

You can water your polytunnel automatically even if it’s nowhere near a tap; all you need is a water tank nearby. The powerful pump will deliver up to 17 litres/min at 35psi (more than mains water pressure).

… or a tap

If you have a water tap in or near your polytunnel, you can connect it directly to the dual zone water valve and leave the pump out.

Efficient with water

Using a combination of sensors (heat, light, and optional soil moisture), WaterMate can change the watering regime based on the conditions in your polytunnel.

On a hot day, more water – so your plants don’t suffer.

On a cool day, or when the soil is already damp; less water, to make your tank last longer.

… or build your own using the WaterMate core pack and extras

The core pack contains:

  • Smart control unit with built in battery
  • Solar panel
  • Dual water valves
  • Temperature sensor

Then choose to add what you need:

  • Hose connector, mini pump or pro pump
  • One or more irrigation pipe kits, or your own pipe
  • A second pump for tank-to-tank transfer

How does the Harvst solar polytunnel watering system work?

A solar powered electronic control system uses environmental sensors, coupled with your choice of timer program, to water plants in two separate irrigation zones. Water can be provided by a pump, or you can use a tap. Settings are managed using an app which runs on Android and iPhone. If you have WiFi in your polytunnel, WaterMate can connect to the internet to allow you to manage & monitor your polytunnel watering system from anywhere. You can also set it up to send you email alerts.

WaterMate is designed and built by Harvst, in the UK. 

Designed for polytunnels

WaterMate has been developed specifically with polytunnels in mind.

Fixings are supplied to attach the LDPE distribution pipe, control unit and solar panel.

If mounting the control unit outdoors, it needs to be in a sheltered place to prevent water ingress. The WaterMate Pro is also available with its own mounting board for this purpose.

Setup videos consider the installation in typical polytunnels.

Smart watering

The control unit uses a combination of heat and light, coupled with a timer routine, to water two zones independently via electric water valves.

You can choose the settings that work best for your layout or plants, using a smartphone app. If your polytunnel is within range of a WiFi network, WaterMate can be set up to send alerts to your email when the greenhouse environment changes.

Also included with the Harvst control app is an interactive garden journal, so you can record what you’re growing, get reminders for re-sowing, and learn more about what you can grow in your polytunnel.

Greenhouse irrigation system

Dual zone watering

WaterMate supports two independent watering zones, using an electric water valve. Each can be controlled using a completely different program, and different sensor inputs. Or, use the two zones to cover a larger area with the one pump.

You could set one zone up for misting/spraying (great for seedlings or salads) and the other zone for drippers (great for plants like tomatoes).

Versatile, flexible, powerful.

What's the capacity of our polytunnel watering systems?

WaterMate Pro can power two separate zones (or 3 zones with a second pump). Each zone could be:

  • 30m of soak hose
  • 120 x drippers
  • 40 x sprayers or misters
  • A combination of drippers, soak hose, sprayers and misters

A sprayer nozzle can typically cover up to 1 metre squared. With a full capacity of 40 sprayers, that’s 40 metres squared of soil. Alternatively, one dripper per plant (eg tomato) means a capacity of 120 tomato plants.

Polytunnel drip irrigation system

WaterMate Polytunnel Irrigation Systems FAQs

Yes, in that you can fit micro irrigation drippers to the hoses, but it is not gravity fed. It’s a high pressure system which helps prevent the nozzles clogging – a common problem with low pressure or gravity fed drip watering systems.  The benefits of drip irrigation include the ability to deliver water only to the roots of a plant – great for watering those that don’t like wet leaves, and helps you save water.

Polytunnel automatic watering can be done in a number of different ways, ranging from overhead misters, to soak hose embedded in the soil, to individual plant drippers and dripper lines. You’ll have different plants growing in different areas of the polytunnel that each need watering in different ways, at different stages of their growth, too. Here’s a way to approach the challenge.

A versatile foundation

You probably don’t want to be setting up your polytunnel watering system from scratch every year, so put the foundations in place which you can modify each season, and throughout the season as plants change. Typically this involves distribution pipes, from which you take off the type of watering you need. 13mm LDPE hose is what we recommend for common small to medium sized domestic polytunnels; you get enough water flow through the pipes and they are not too cumbersome to manage.

A range of outlets / emitters

Your salad might want misting or spraying. Your tomatoes would prefer drip feeding or bottom feeding. A tray of seedlings would like a combination of spraying and bottom watering. A perfect automatic polytunnel watering system will need to deal with all these situations.

The Harvst WaterMate Pro has two separate watering zones, which helps with the first level of separation. You can have one zone for distributing water around your polytunnel to dripper lines, and the other zone for spraying and misting. With taps in suitable places, you can choose which physical areas in your polytunnel get misted, and which get drippers.

A high flow rate

Polytunnel watering can consume a lot of water, so whatever automatic watering system you use you’ll need to make sure it can provide enough flow to supply all the outlets you are using. The smaller, high pressure pumps used in many plant self watering systems simply don’t provide enough flow for a larger area. You’ll get some water to the first few outlets and then the rest will be dry. The 3 gallon per hour pump supplied with the WaterMate pro will feed up to 60 outlets per watering zone at a good flow rate.

Good water pressure

Flow rate isn’t all you need. You’ll need the pressure to push water through all the pipes, up into the roof, and deal with the long pipe runs encountered in a polytunnel. A small, camper-van style pump might claim 15 litres per minute, but when you connect it to a long pipe system, it won’t have the pressure to get the water through.

Solar powered

Most polytunnels don’t have mains electricity available, so any automatic watering system for a polytunnel will need to be solar powered. Coupled with the need for a powerful pump which draws significant current, this doesn’t leave you with many off-the-shelf options. Your solar generating capacity will need to match or exceed your pumping power drain – even better if the automatic watering system can monitor your battery capacity and adapt the automating watering appropriately.

No! WaterMate will run fine without WiFi. The system will transmit its own WiFi signal, which you can connect to when you are within a few metres of the control unit. 

The WaterMate Pro can power two separate zones (or 3 zones with a second pump). Each zone could be up to:

  • 30m of soak hose or
  • 120 x drippers or
  • 40 x sprayers or misters or
  • A combination of soak hose, drippers, sprayers and misters

A sprayer nozzle can typically cover up to 1 metre squared. With a full capacity of 40 sprayers, that’s 40 metres squared of soil. Alternatively, one dripper per plant (eg tomato) means a capacity of 120 tomato plants.

You will need to log on to the Harvst web app, using a smartphone. From there, you have access to the following settings for two zones:

  • How long to water for; from 1 second to 5 minutes
  • When to water; from twice a day to once every 5 days
  • Solar boost; when it’s been hot and sunny for more than 4/6/8 hours, to give extra water
  • Water when the soil is dry
  • Skip watering when the soil is already damp

Watering is automatically reduced on cloudy, overcast days.

Everyone’s use of our WaterMate is different, so there is no ‘correct’ way to set up your irrigation pipes. We recommend that you have the two watering zones set up with distribution pipes around the perimeter of your greenhouse, polytunnel, or beds – with either sprayers inserted directly into the pipe, or with take-offs at regular intervals for rings of drippers on a 4mm hose.

You would use drippers for larger plants where you know exactly where the water is needed, and use sprayers for larger areas of plants (such as salads), or for seedlings.

Yes, you can. The WaterMate Pro pump is capable of powering at least 15m of hose. It will cycle on/off once the hose has reached pressure.

Yes, you can. The WaterMate Pro pump is capable of powering at least 20 mister outlets per zone.

The solar powered WaterMate Pro runs on a battery, limiting power which means you cannot directly run heaters or lights. However, the mains powered versions of the WaterMate can run heating and lighting.

Each zone can be set to water from 1 second to 5 minutes at a time. Five minutes might not sound like much, but with water being delivered to the whole area at once, this is a significant amount of water. The pump is rated at 12 litres per minute, which reduces to approximately 10 litres per minute when you have the valves, nozzles, drippers etc connected. Five minutes would be 50 litres.

Yes! WaterMate will work fine with a tap, so you won’t need a pump. Select the garden hose choice when you order. The hose (which must be left turned on) simply connects to the dual watering zone valves which act as an electric tap.

Yes, you can. We provide an alternative control unit which does not need the solar panel. The mains version comes with extra outputs for additional pumps, heater cables and/or grow lights.

The WaterMate Pro pump can provide water for many tens of metres of pipe, and up to 5m of vertical head. If you add too many drippers and water outlets to the line, the flow rate per outlet will drop. Too long a pipe and your first outlets will start working a long time before your last ones, leading to overwatered plants at the start and under watered plants at the end. Try to set up your irrigation system in a ring.

We provide 4m of inlet hose (between the water tank and the pump) but the system will run with at least 10m of inlet hose and a 4m vertical head. The pump is self priming.

Yes. If you’re in the polytunnel, you can either use your smartphone or you can use the button on the control unit if you don’t have your phone with you.

We provide a versatile solar panel mounting bracket, which is screwed to a wall or post. You can place the solar panel in the optimum position for sunshine (outside the polytunnel or greenhouse is best) up to 3m away from the control unit. Solar panel extension cables are available.

The powerful self priming pump does not suffer from air locks, so if your water tank runs out and then refills later, the system will have no problems restarting, without you needing to prime it.

It’s remarkably quiet for such a powerful pump. It’s mounted on rubber feet, and if you place it in a suitable location you probably won’t hear it running at all!

WaterMate has automatic frost damage protection. It will not run the pump if the temperature falls below 1 degree centigrade.

We’ve designed the system to work with any off-the-shelf irrigation and micro-irrigation parts. The kits are provided with 13mm LDPE pipe, 4mm micro irrigation kits, and a selection of spray nozzles for you to experiment with. When you have decided what you like, you can add more.

Yes, all components are available as replacements or upgrades. There is a 2 year manufacturers warranty on all major components. Warranty on batteries in solar units is 1 year from purchase.

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