• The use of mains water in England and Wales is regulated by the Water Supply (Water Fittings) Regulations 1999, an Act of Parliament which lays down what can and cannot be done with drinking (potable) water supplied by the water companies. The Act contains two important principles: water should not be wasted and water should not be contaminated. In order to comply with the first principle, it is important that the water provider is contacted before an irrigation system is installed, with information on what system is being proposed. To comply with the second principle, all irrigation systems must have some means of back-flow prevention. Depending on how the water is used, the law assigns a risk category from 1-5. Category 3 allows use of fixed head sprinkler systems with the sprinkler heads no less than 150mm above the ground level. When using hoses, or any other irrigation nozzle located below 150mm, then the risk category is category 5. For irrigation systems which fall into category 3, a ‘Type EC’ verifiable double check valve or ‘Type ED’ non-verifiable double check valve is sufficient protection. This needs to be fitted into the pipework and protected from frost. For irrigation system in category 5, such as dripline and sprinklers below 150mm, a ‘Type A’ airgap is normally required. Most domestic cold water tanks have a ‘Type B’ arrangement, so it is important to ensure the break tank is designed for irrigation. ‘Type A’ airgaps consist of an inlet valve which is positioned above the highest possible water level of the tank. This eliminates any possibility of the inlet valve being submerged, and water from the tank being drawn back into the mains water supply. With a ‘Type AA’ airgap, the rim of the tank forms an overflow and the inlet valve is positioned above the tank rim. With a ‘Type AB’, a large overflow weir is cut into the side of the tank to prevent the water level reaching the inlet valve. As ‘Type A’ airgaps result in the mains water pressure being lost, a pump is then needed to re-pressurise the water supply. Vertical or horizontal electric pumps are normally used for this purpose, normally under the control of an irrigation timer or an auto-start device. Access Irrigation can supply compliant water storage tanks, and also produce a range of pressure booster units which combine a break tank with a pressure booster set. Note: If the irrigation system is to be installed in a private, single occupancy dwelling (referred to as a ‘Domestic’ or ‘House Garden’ in the regulations) then there are slightly less stringent rules apply – see blog post ‘Water Regulations for Domestic Gardens’.

  • Drip irrigation systems are designed for use in large scale horticulture and agriculture, where the cost of water; or the scarcity of water precludes sprinkler systems. In landscape projects, drip irrigation systems are normally designed where the project requires very unobtrusive watering, such as public spaces, or the planting is incorporated in hard-to-reach planters or troughs. A drip irrigation system designed for field scale crops will generally use either a buried drip tape with a relatively thin wall disposable drip tape under crops of 1-3 seasons duration; or a thicker walled drip pipe either on the surface or sub-surface for longer duration crops such as vines or orchards. Sub surface drip systems are more economical in terms of water efficiency, but can be more prone to accidental damage. The design of the drip irrigation system needs to take into account the pressure losses in the pipework on long runs and also the topography of the field - sloping or undulating sites may need non-leakage design drippers to prevent water from leaking from the low points once the system has been turned off. For landscape drip irrigation designs, thick walled drip lines would generally be used to water border areas - either pegged to the surface of buried under a mulch. Drip lines in a landscape setting are more prone to damage from maintenance staff, so a thick walled pipe is essential. Drip lines on larger beds would be spaced at approximately 0.5m apart across the bed. For smaller planters the drip irrigation system will need to be designed to bring water to each individual planter - generally using micro-bore drip pipe and drippers. Ideally on landscape projects the supply pipes for the drip irrigation system would be installed during the initial build process to ensure all of the supply pipework is hidden away. To design a drip irrigation system a plan of the site is required along with information on the available water supply. For agricultural projects water can be taken from rivers, storage ponds or rainwater catchment areas such as farm buildings. For landscape projects mains water is generally used but water regulations generally require break tanks for back-flow prevention. The drip irrigation system can then be designed and pipe work sizes and quantities calculated.

  • Understanding Domestic Water Supply Regulations Most people are unaware that there are legal requirements to take into consideration when connecting an irrigation system to a domestic garden tap. This simple guide provides you with the information you need to make sure you stay on the right side of the law! What you can connect to the mains water supply is regulated by an Act of Parliament - the Water Supply (Water Fittings) Regulations 1999; these regulations supersede the old water bylaws in England and Wales. Double Check Valves on outside taps If you are a domestic house then you must have a double check valve on all 'hose union' taps - outside taps to you and I. The double check valve is designed to prevent water and contamination flowing backwards from the garden and into the water main. Water companies regard the water in your garden hose as high risk as it may have all sorts of contaminants in it from the ground. With a double check valve fitted, then you can run border sprinkler systems which have their sprinklers more than 150mm above ground level. You can also use a hand-held hose. DB Valves for back-flow protection If you want to run a drip system (either for borders or hanging baskets) then you also need a DB Valve. This is a special valve which fits onto the tap or after a timer which again prevents back-flow. The Water Companies regard these systems as higher risk as they will definitely have outlets next to the earth. You still need the double check valve as well, but the DB Valve provides a 'belt and braces' solution. The DB Valve has to be fitted higher than the highest dripper and has to be fitted after the tap or timer, as it will not stand full mains pressure for prolonged periods of time. If you have multiple garden irrigation valves controlled from a single irrigation controller, you can use the 'master valve' option on most controllers to protect the DB valve from excess pressure. A DB valve works in a different way to a double check valve, so the Water Companies regard it as a 'belt and braces' approach. One of the sad things about many of the 'consumer' irrigation companies is they never tell the customer that a DB Valve is necessary to comply with the law. If you want to run pop-up garden sprinklers in the lawn, as these are underground these need an even higher level of backflow protection, with an air-gap tank installed with a pump.

  • Specifying a pump on an irrigation system will boost available pressures and water flows, allowing larger zones and enabling more thirsty items such as pop up sprinklers to be used, however the pump also needs fittings on the inlet and the outlet to connect it to the water source and ensure that it will run reliably. In this video, Mike Briley from Access Irrigation talks through the options for surface mounted pumps and also submersible irrigation pumps. All pumps and fittings are available from Access Irrigation, along with friendly and helpful advice.    

  • Small irrigation systems such as drippers can generally be run off the mains water supply without problems, but as water flows get larger there is the danger that the water supply will not be large enough. In addition, sprinkler systems require a certain pressure to operate. If there is too little flow or pressure then the irrigation system will not work properly. To ensure the irrigation system will work as planned it is vital to have some flow and pressure information from the water source. With this information available we can then ensure that the system is designed around the available supply - if the pressure is too low a pump can be specified. If the flow is too low the irrigation system can be divided into zones to ensure there is always enough water to operate the irrigation system. Although it may seem like extra work to obtain the pressure and flow data, it will save embarrassment later on when the irrigation does not work properly, and the cost of relaying pipes and adding extra valves to remedy the situation at a later date. Measuring the flow and pressure This video explains the equipment needed and the process of measuring the water flow. You will need a pressure gauge and a bucket with litre graduations. The process is briefly outlined below: 1. Obtain a static pressure - with the outlet valve closed measure the static pressure on the gauge. In the video this was just under 4 bar, which is very good for a domestic supply. 2. Obtain flows at set pressures - as the outlet tap is opened the pressure will drop - the more flow the lower the pressure. We wish to obtain flow readings at 3.0, 2.0 and 1.0 bar. To do this we shall slowly open the tap until the dial on the pressure gauge is reading 3.0 bar. If you are using a smaller container, time how long it takes to fill the container at this pressure and note it down. If you are using a large container as in the video, time how long it takes to fill from one marked capacity to the next mark. Note the flow and the volume you have filled. Open the tap slowly until the pressure gauge reads 2.0 bar and repeat. Repeat for 1.0 bar. 3. Once you have the data you need to translate the flow into litres per hour. To do this divide the capacity by the time it took. For example when the flow was measured at 3.0 bar, if the bucket had 5 litre graduation marks and it took 20 seconds, divide 5 (litres) by 20 (seconds). Then multiply the result by 3,600 (the number of seconds in an hour). Eg. 5 divided by 20 times 3,600 = 900 litres per hour. Pressure and Flow: 3.0 bar 900 l/h 2.0 bar 1,240 l/h You will notice that as the pressure falls the flow increases 1.0 bar 1,450 l/h 4. Once you have calculated the flow for each of the pressure points, either send the information to us along with the plan of the garden, or plot a graph of the data to help you design the system yourself. Note: A simpler, but less accurate, method is to measure the flow and pressure with the tap 3/4 open and 1/4 open.  

  • This extraordinary vertical forest is being constructed in Milan as part of two residential towers. The towers house of 730 trees, 5,000 shrubs and 10,000 plants. These drawings of the building were produced by Stefano Boeri, Gianandrea Barreca, and Giovanni La Varra, the architects who designed the project for the firm Boeri Studio. The architects state that in addition to being pleasant to behold, the two towers will help purify the city air, increase bio-diversity and protect residents from the sun and noise pollution. By bringing the plants into the city, they also aim to reduce the effects of 'urban sprawl'. For wildlife, especially birds and insects a haven in the middle of one of Italy's largest cities will be of enormous benefit. Tree-planting recently began on the structures, but not before the architects spent some two years working with botanists to determine which varieties and sizes would best suit their purpose. Once the project is finished later this year, they will be watered mainly with grey water produced by residents, and tree care will be managed by building staff at the towers. With so many plants to water, the design of the irrigation system must have been right at the heart of the project. Although we do not know the details, drip watering systems will have inevitably been used to bring water to the root zones of each plant. The irrigation system has been designed to use grey water from the showers and sinks in the building. This will have then been stored and filtered before being pumped into the irrigation system. One of the challenges of using grey water is the soap content, as this will clog conventional drip nozzles if the levels are too high. Companies such as Netafim have pioneered drip lines able to cope with grey-water systems, as well as filtration systems.  

  • With the UK's temperate climate, many people ask if it is worth irrigating. In this article we look at the benefits of irrigation. Covered Areas and Restricted Root Zones Where planting is under cover or experiences rain shadowing from tall buildings, irrigation is essential to keep the planting alive. If trees are planted in urban areas, with hard landscaping around the root area, irrigation will be needed to supply the trees water needs. Even medium sized trees require 100 litres per day in dry weather. Modern control systems can be programmed to take rainfall into account when scheduling outdoor irrigation zones while ignoring rainfall for covered or rain-shaddowed   Speeding up Establishment  Where planting needs to mature quickly or is being used as screening, irrigation will greatly speed up the process. As the graph indicates, during the bulk of the UK growing season, plants experience a Water Deficit. This graph is for an 'average' English year, for a '1-in-5' dry year the deficit is even greater, as the rainfall levels are lower and the Evapo-transpiration (ET) levels are higher, widening the deficit between the two. As plants require water as part of their growth process unless this deficit is made up by irrigating, their growth will be reduced. As a rule of thumb irrigated landscape planting will establish approximately 50% faster than non-irrigated plants.   Reducing Plant Losses  As landscape contractors generally have to provide a warranty with the plants, costs due to plant failure can be expensive, especially if there is an unusually dry spell. The cost of integrating an irrigation system into the planting scheme is often quite small compared to the cost of the planting. In addition, the irrigation can often be sold to the client as part of a 'value added' package. The lack of water during the growing season not only limits the potential growth of the plants, it also increases the likelihood of diseased plants and specimens that do not survive. The cost of the labour in replacing the plant needs to be taken into account along with actual cost of the plant itself.   Reducing maintenance costs During the first few weeks after Summer planting the plants will need to be watered regularly. Turf will quickly shrink back and die and planting into dry borders will struggle. An irrigation system can automate the task, saving many hours of time on-site.   Green Roof Systems Soil is very heavy, so the deeper the substrate, the stronger the roof structure needs to be. As the strength of the roof increases, so does the carbon footprint of the building. By using a lightweight green roof structure, the load bearing structure of the building can be reduced, but the planting will quickly dry out.  Using innovative control systems that only water after a prolonged dry spell, irrigation can ensure the plants thrive while ensuring precious water is not wasted. The use of irrigation also ensures that the sedum mats do not dry out and become detatched from the roof.   

  • Porous hoses and ‘Leaky Pipe’ type drip systems are very popular; but are they as technically capable as commercial drip lines such as Permadrip? One consideration when designing and irrigation system is the output. Not only do we need to know how much water is being applied, we also need to be sure that the amount of water supplied at to the plants at the start of the system will be the same as the plants situated at the far end. If not, some plants will be too wet – wasting water, whilst others will be too dry. With Permadrip, each dripper is ‘pressure compensated’ so every dripper delivers the same amount of water (1.6 litres per hour) regardless of whether the dripper is at the beginning of the run or the end of the run*. In contrast may porous pipe systems can only give a rough indication of output, and this output will fall along the length of the pipe. Another vital consideration when specifying drip lines is the life expectancy. Permadrip is made of a thick walled, UV stabilised polythene with a 10 year life expectancy. Although a filter is always recommended, each dripper has a built-in self-flushing mechanism to minimise any blockage problems. Porous pipe systems, by contrast have extremely small dripper ‘pores’ that are much more prone to blocking over time. Porous pipe systems release water along their entire length to create a continuously watered band, whereas Permadrip have drippers every 300mm or 500mm – which is better? With Permadrip, as the soil surface is kept mostly dry, evaporation losses are reduced and weed growth discouraged. Beneath the soil surface, the capillary action of the soil will cause the moisture to spread outwards in an inverted cone shape, ensuring an adequate water supply to the plant roots. Permadrip is manufactured as a commercial grade product in state-of-the-art manufacturing facilities. Manufactured in Israel by some of the world’s leading irrigation manufacturers, the drip line is the product of many year’s R&D effort.

  • One benefit of working in irrigation are the fascinating schemes that we get involved in. One such scheme was in Bristol, where the docks had been dredged for seeds amongst the discarded ballast from sailing ships that had used the docks 300 years ago. The seeds have been germinated and, with help from Bristol University's Botanic Garden, identified. The diverse range of plants includes: Nigella Damascene from Southern Europe, Camelina Sative from Northern Europe and Central Asia and Gilla Capitata from North America. The seeds have been planted on a disused grain barge, moored in Bristol's Floating Harbour. For more information, follow this link.

  • According to the above headline in Garden Trade News, The Old Railway Line Garden Centre is aiming to reduce its water bills by 60% using 4 rainwater storage tanks with a combined capacity of 10,000 litres. Stories such as these underline the potential for Garden Centres and Nurseries to slash their water bills and reduce their environmental footprint at the same time. Glasshouses and buildings all provide plenty of potential to catch large amounts or rainwater, and above ground galvanised storage tanks provide large tank capacities at an economical cost. Access Irrigation have many years' experence in designing and supplying rainwater catchment systems. Tanks can either be above ground or underground, and depending on the site layout, water can either fill the tanks by gravity or be pumped from catchment sumps to more remote tank locations. During dry spells the tanks can be topped up automatically from the mains water supply. For more information on how Access Irrigation can design and supply Rainwater Harvesting systems visit our website and download our free PDF guide.

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