Welcome to Combined Harvesters.com

Formed in November 2006, Combined Harvesters have striven to become the foremost suppliers and fitters of all types of rainwater harvesting systems from simple water butts to full underground storage systems and all associated integral parts.

We, unlike a great many companies, are not affiliated with one supplier but source our products based on market trends and the specific needs of our clients.
With such a comprehensive range of water butts,rainwater tanks,hosepipes,hose fittings,pumps, filters, diverters etc.on offer,we believe our service to be second to none in the industry and one which we continually strive to improve.

Our business history is not quite so young as Combined Harvesters however, we have been in landscape construction and design for 25 years in both the domestic and commercial sectors which has given the team great knowledge and experience to bring to this blossoming sector.

When you deal with us, you are not only getting fast, friendly advice from a family owned and run company but you will get the benefit of our integrity and business skills to give you the most comprehensive system, specifically tailored to your needs within your budget.

What more can we say except happy surfing!

If you do not see what you require...give us a call 0845 838 7542(Local rates apply) or ask for one of our surveyors to visit. The service is without obligation, we do not employ sales persons, cold calling, junk e mail or unpleasant sales techniques.

Rainwater Harvesting (general)

The new buzzword that will be heard over the next few years will be 'rainwater harvesting'. We live in an increasingly environmentally aware society, and one that is ever conscious of frugality with regard to our necessary expenses.
Combined Harvesters have amalgamated existing products with new, innovative and exciting systems to provide a 'one stop', comprehensive approach to the harvesting of natural rain water and the attenuation of storm water. This water is practically chemical free and a great source to irrigate arid gardens, wash the pride and joy on a Sunday, or feed the toilets...and of course there is no burden of guilt during the ever longer periods of water restrictions.

When fitting a system, it is important not to oversize or undersize the tank. Apart from the obvious additional cost, a well designed system has a regular and consistent overflow, removing fine debris from the water surface and keeping the water quality fresh. Below is a simple calculation to establish a guide to your required tank size. Available rainfall = Annual rainfall for your area(mm)x Roof area(m2)xEvaporation factor*x Filter loss factor* *Assume as 0.9 E.G. Typical 3 bed house the yield would be: 800 x 120m2 x 0.9* x 0.9* = 77,760 Litres Expected usage 45 % x 150 litres per person per day E.G. Typical 4 person household 150 x 4 x 365 x 45% = 98,550 Litres If you calculate 5% of the lower value, then a tank size of 3,888 litres is suitable or one that is closest to this figure. The benefits of a modular system are that additional tanks can be joined at a later date with ease.

Of course, the same calculation can be used for commercial organisations, who can increase their BREEAM status ( Building research establishment environmental assessment method ), whilst taking advantage of products listed on the water technologies list, making them eligible, to off set 100% of their expenditure from due taxes at the end of the fiscal year.

Combined Harvesters – Rainwater harvesting solution specialists – 0845 838 7542

Case Study

Enquiry from a lady living in a rural location in Buckingham.

Requirements

1. Irrigation of a newly acquired area of land adjacent to her property (arable use)
2. Supply of rainwater to a naturally filtered ‘swimming pond’
3. Supply of 2 x above ground tanks to feed a small swimming pool and general domestic irrigation to a small garden.

Specifics
• Prevalence of bed rock, high to the surface (approx 1.5 metres)
• Interceptor in lane adjacent to property.
• Roof surface area – more than adequate.

Solution

• Supply of 2 x 3000 litre ‘Rondus’ underground tanks with pedestrian lids.
• 1 x ‘Optimax’ internal filter with calmed inlet and overflow siphon.
• 1 x ‘Intergra duo’ jet pump with floating intake
• 2 x 700 Litre above ground ‘Rain catcher’ tanks with separate filter diverters, gravity feeding domestic irrigation system and pool.

Rainwater Harvesting for the commercial sector:

Why harvest rainwater ?

Financial considerations ?

Enhanced Capital Allowance (ECAs) enable a business to claim 100% first-year capital allowance on their spending on qualifying plant and machinery. There are three schemes for ECAs:
Energy saving plant and machinery.
Low carbon dioxide emission cars and natural gas refuelling infrastructure.
Water conservation plant and machinery.
Businesses can write off the whole of the capital cost of their investment against their taxable profits of the period during which they make the investment.
This can deliver a helpful cash flow boost and a shortened payback period.

Water related areas covered by the scheme include:

• Cleaning in place equipment
• Efficient showers
• Efficient toilets
• Efficient washing machines
• Flow controllers
• Leakage detection equipment
• Meters and monitoring equipment
• Rainwater harvesting equipment
• Small scale slurry and sludge dewatering equipment
• Vehicle wash water reclaim units
• Water efficient industrial cleaning equipment
• Water management equipment for mechanical seals
• Efficient membrane filtration systems

A typical payback period for a commercial system is three years.

Environmental considerations ?

In recent years, important changes have taken place in the design philosophy associated with the collection and disposal of stormwater run off. Traditional drainage practice is designed to move rainwater as quickly as possible to a watercourse or river. This is normally achieved via gravity pipelines or culverts. However this approach is now being reviewed because of the following factors:

• The governments latest estimates suggests a twofold increase in the number of house starts each year. This increase in the built environment results in a reduction of permeable surfaces.
• By diverting surface water run-off to piped systems, the ground waterlevels are reduced.
• Existing stormwater drains are becoming increasingly overloaded.
• The difficulty in locating water with the capacity to accept increased flows, without the risk of flooding.
• Surface water run off can contain contaminants such as oil, organic matter and toxic metals. Although often at low levels, culmulatively they can result in poor water quality in rivers and ground water.
• Increasingly extreme weather conditions due to climate change.

Sustainable drainage systems

The philosophy of sustainable drainage systems or SUDS is to mimic as closely as possible the natural drainage from a site before development, and to treat run-off to remove pollutants.
A sustainable drainage system provides several benefits over conventional systems. Correctly designed, installed and maintained, SUDS can improve the management of surface water run-off for most developments.
• Reducing peak flows to watercourse and sewers, reducing flood risk downstream.
• Improving water quality by reducing the levels of silts and pollutants.
• Reducing potable water demand through rainwater harvesting.
• Replicating natural drainage patterns, including the recharge of groundwater.

Infiltration

Infiltration systems store water temporarily. With the potential to provide a cost effective solution to many site drainage problems, they are generally divided in to two categories depending upon whether temporary storage of water takes place above or below ground level.
Above ground infiltration systems utilise natural or artificial surfaces. Their shape and size may vary considerable from near level surfaces to basins and swales that have distinct sloping sides. Typical examples include porous pavements and paviours basins and swales.
Below ground or sub-surface infiltration systems offer temporary storage of surface water below ground level. Conventional soakaways are the most common example, although alternative options include the use of trench style soakaways and infiltration blankets that utilise pipe work over a large plan area for dispersal.

Attenuation

In principal this consists of the temporary storage of surface water in a suitable chamber below ground level. This chamber needs to be of sufficient size to accommodate the calculated run off during peak periods of rainfall. The stored water is then gradually released in a controlled manner into a surface water or combined drainage system, or watercourse, subsequently eliminating the risk of flooding.

Traditional methods of attenuating flows include the use of tanks and oversized pipes to create the storage chamber with outlets being controlled by downstream throttles, orifice plates, hydraulic controls or valves.

Increasingly, as existing sewer networks approach their capacity, attenuation systems offer a cost effective solution for accommodating additional catchments without increasing the size of existing sewers.

It is now commonplace on brownfield developments for sewerage undertakers to limit additional flow into existing sewers to a level equivalent to that of the original run-off. In these situations an attenuation device will be required.

• Infiltration and attenuation reduce the quantity of water requiring conveyance in any piped system downstream of the development and decrease the flow in stormwater sewers the risks of discharge from overflows in combined sewer systems.

• Infiltration may be used where there is no convenient existing storm drainage system to which connection can be made.

• By controlling stormwater close to source, infiltration and attenuation drainage reduces the hydrological impact of urbanisation.

• Infiltration and attenuation may be used where existing piped systems or treatment works are near or at capacity loading.

• Infiltration can be used to enhance recharge to groundwater in situations where the quality of stormwater runoff does not pose a threat to groundwater quality.

• Construction is normally simple and rapid.

• Whole-life costs may be less than for alternative systems

It should be also noted that;

• The performance of infiltration systems depends on the properties of the soil in which they are constructed

• Field tests are necessary in order to determine infiltration coefficients for design purposes.

• Water table must be known.

Rainwater harvesting

A relatively new concept, rainwater harvesting is the storage of stormwater discharge locally for re-use in non-potable applications such as garden irrigation, toilet flushing etc.

With the increasing demand for drinking water as a result of high density housing and commercial development, rainwater harvesting is seen as a potential solution for overcoming water shortages. It is widely considered that this may well be the subject of future legislation.

What regulatory requirements are there for rainwater harvesting systems?

There are currently no direct building regulations for rainwater harvesting. However, drainage is covered by the Building Regulations and can influence rainwater harvesting system design such as soakaway or city drain connections for tank overflow. Several other associated regulations apply; In England and Wales the Water Supply Regulations 1999 (Water by-laws 2000 in Scotland and Water Supply (Water Quality) Regulations (Northern Ireland) 2002) must be adhered. These regulations are enforced by the water supplier. The essential requirements of the regulations specific to rainwater harvesting are; (1) no cross bonding of rainwater piping with potable supply pipes (2) prevention of backflow to potable water supplies according to CEN EN1717 or air gaps type AA/AB/AC etc (3) the clear marking of rainwater pipes according to WRAS # 9-02-05 and (4) material specifications, where contact with wholesome water is permissible meet the prevailing approved list.
What is unique about Combined Harvesters systems?

Combined Harvesters have a focus on direct systems with factory built appliances enabling simple and fast installation. End user maintenance is reduced and whole life costs are lower. The PE and PP tank ranges have smooth internal surfaces that are easy to clean during long term maintenance. Using high performance multi-stage pressure pumps built into factory assembled and tested appliances long term reliability is assured and the need to enter the tank for pump maintenance is eliminated.
We offer a highly efficient, experienced and committed service to all our clients alike from project conceptions to completion and beyond.

A percolation test
A hole 300mm ² should be excavated to a depth 300mm below the proposed invert level of the effluent distribution pipe. Where deep drains are necessary the hole should conform to this shape at the bottom, but may be enlarged above the 300mm level to enable safe excavation to be carried out. Where deep excavations are necessary a modified test procedure may be adopted using a 300mm earth auger. Bore the test hole vertically to the appropriate depth taking care to remove all loose debris.
Fill the 300mm ² section of the hole to a depth of at least 300mm with water and allow it to seep away overnight. Next day, refill the test section with water to a depth of at least 300mm and observe the time, in seconds, for the water to seep away from 75% full to 25% full level (ie, a depth of 150mm). Divide this time by 150mm. The answer gives the average time in seconds (Vp) required for the water to drop 1mm.
The test should be carried out at least three times with at least two trial holes. The average figure from the tests should be taken. The test should not be carried out during abnormal weather conditions such as heavy rain, severe frost or drought.
Drainage field disposal should only be used when percolation tests indicate average values of Vp of between 12 and 100 and the preliminary site assessment report and trial hole tests have been favourable. This minimum value ensures that untreated effluent cannot percolate too rapidly into ground water. Where Vp is outside these limits effective treatment is unlikely to take place in a drainage field. However, provided that an alternative form of secondary treatment is provided to treat the effluent from the septic tank, it may still be possible to discharge the treated effluent to a soakaway.

Rainwater Harvesting...some interesting facts.

England has less water available per person than any other country in Europe. It will come as no surprise to homeowners that New Legislation states that water companies now have the right to compulsorily meter all of their customers.

The harvesting of rainwater is a relatively simple concept, however the majority of homeowners are unaware of its benefits. Rainwater harvesting is the collection of water that would otherwise have gone down the drainage system, been lost through evaporation or soaked into the ground. Collected rainwater has predominantly been employed for outdoor purposes, however the use of rainwater inside the home is becoming more favourable as water costs increase.

Water is currently metered at between £1-2 per m³ and is expected to steadily increase as prices have already risen by 50 per cent since privatisation. At present, around 25 per cent of UK households are metered but New Legislation brought in this year allows water companies the right to meter all of their customers. With New Legislation, increasing water costs and enforced hosepipe bans, the benefits of harvesting rainwater become apparent.

Rainwater harvesting systems can be installed in both new and existing buildings. Toilets, washing machines and outdoor use account for 50 per cent of domestic water consumption. If correctly harvested and stored, rainwater can be used for all these requirements without further treatment. At present there are no UK regulations concerning rainwater use for toilets, washing machines and gardens, however the back-up from the mains must comply with the Water Supply Regulations 1999. Rainwater can be advantageous for washing purposes as its composition and softness reduces the need for harsh detergents. Rainwater is naturally soft and doesn’t contain the chalk and lime deposits that are found in hard water. It is these mineral deposits which cause the build up of scale and scum around baths and basins.

The minerals contained in hard water settle as a deposit of scale whenever the water is heated or when cold standing water evaporates. Over time, hard water can have a devastating effect on pipe work and can cause premature failure of water heaters. It is estimated that in Germany 100,000 rainwater systems are installed every year and recent trails have shown extended life for washing machines that run on rainwater.

Mains supply water is chemically treated to remove impurities to produce pure drinking water. However, treated water is not needed for any other use apart from human consumption. Rainwater collection removes the need for the energy and chemicals used to produce drinking water which seems unethical to simply flush down the toilet or wash the car with. Studies have proven that rainwater is actually beneficial for the garden and the car as it contains a lower amount of Total Dissolved Solids (TDS) than normal mains water. TDS refers to any amount of cations, anions, minerals, salts or metals dissolved in water. Some dissolved solids are from organic matter such as leaves, pesticides and industrial sewage.

The TDS rating is naturally high in hard water which over time can cause a significant build-up of lime scale and the chlorine can have a detrimental effect on gardens and cars. In a recent study the TDS levels of rainwater and mains supply water were tested: the TDS results for the mains water was 228 compared to 45 for the filtered rainwater. The lower the TDS rating, the purer the water therefore the test concluded that rainwater is purer than mains supply water.

There are also environmental benefits of harvesting rainwater as by utilising rainwater efficiently the demand on rivers and groundwater is greatly reduced. The World Wide Fund (WWF) recently reported that over-extraction by water companies is damaging Britain’s wetlands and trout rivers. The problem is most apparent in the South East where the population is increasing and the need for new housing is putting extra pressure on the decreasing water supply. Rainwater harvesting also reduces the need for the pumping of mains water which causes pollution and CO² emissions. Rainwater management can lower the volume of water in sewers and storm water run off is reduced helping to solve flooding.

Water rates look likely to continue their upward trend therefore rainwater conservation begins to look more attractive to the homeowner. Over half of all domestic water usage such as washing machines, toilets and gardens doesn’t require treated water from the mains supply. The case for harvesting rainwater speaks for itself: by conserving rainwater, the potential savings in water rates are very significant and, more importantly, the dependence on mains water is diminished. Sustained water savings can add value to a property as well as demonstrating a level of commitment to helping preserve the environment and its natural resources.

Sustainable drainage solutions or stormwater management. S.U.D.S.

The innovative design of Waterloc utilises columns of extruded polypropylene honeycomb structure, already widely used in stormwater storage applications, in a unique combination with injection moulded grids enabling rapid dispersion of water throughout the installation. Waterloc is strong and lightweight and suitable for pedestrian and lightly trafficked areas. The cells can easily be used in a modular format to for a stormwater storage unit configured to suit the capacity required, soil conditions and the land area available. Please request information on Waterloc HD which is lightweight (14kg) and suitable for heavy trafficked areas and installations deeper than 2 metres. Storage capacity - 250 Litrre Vertical Loading - 20 t/m2 Weight 10KGS Dimensions 800 x 600 x 520 Void Ratio 96% The connectors which are listed seperately are designed to be fitted 'back to back' and can be configured for use either on an upper face or between layers of cells. Once the base layer of Waterloc cells are in position and leveled, successive layers can then be built up using the connectors between each layer. Please ring for quotes on quantity orders-0151 334 8655 Details now available on the Flowloc control device; flowloc, silt trpa, inlet filter, riser and orifice plate, the new addition to the waterloc range of products wiht a vortex flow control device, to be used as part of an attenuation scheme..

A percolation test
A hole 300mm ² should be excavated to a depth 300mm below the proposed invert level of the effluent distribution pipe. Where deep drains are necessary the hole should conform to this shape at the bottom, but may be enlarged above the 300mm level to enable safe excavation to be carried out. Where deep excavations are necessary a modified test procedure may be adopted using a 300mm earth auger. Bore the test hole vertically to the appropriate depth taking care to remove all loose debris.
Fill the 300mm ² section of the hole to a depth of at least 300mm with water and allow it to seep away overnight. Next day, refill the test section with water to a depth of at least 300mm and observe the time, in seconds, for the water to seep away from 75% full to 25% full level (ie, a depth of 150mm). Divide this time by 150mm. The answer gives the average time in seconds (Vp) required for the water to drop 1mm.
The test should be carried out at least three times with at least two trial holes. The average figure from the tests should be taken. The test should not be carried out during abnormal weather conditions such as heavy rain, severe frost or drought.
Drainage field disposal should only be used when percolation tests indicate average values of Vp of between 12 and 100 and the preliminary site assessment report and trial hole tests have been favourable. This minimum value ensures that untreated effluent cannot percolate too rapidly into ground water. Where Vp is outside these limits effective treatment is unlikely to take place in a drainage field. However, provided that an alternative form of secondary treatment is provided to treat the effluent from the septic tank, it may still be possible to discharge the treated effluent to a soakaway.

Our range of accessories.

Thank you for visiting us at Combined harvesters rainwater harvesting specialists. We take pride in being the foremost suppliers of rainwater harvesting and storm water management systems to the European market. Our main range of products centre around the following categories-:
Rainwater storage tanks, water butts, rainwater filters and diverters, storm attenuation systems (suds), Control units, pumps, irrigation systems, grey water systems and of course our own rain catcher range of above ground rainwater storage tanks and systems. Allow me to take these items in order.
Our rainwater harvesting systems have been sourced from the best possible manufacturers in the industry such as graf, blackwall, even greener, be green, sankey,3p technik, harcostar, marley, conder, polypipe, wavin, and many more respected companies.
We are proud to offer garden tanks, rainwater storage complete systems and sustainable drainage systems at highly competitive rates. In fact we have a price matching service available, if you find cheaper for the same product then we will either beat or match that price.
Our water butt range comes from suppliers in the uk, either injection moulded or rotationally moulded, giving a huge choice for products. Our range of rainwater harvesting systems are explained deeper in their relative categories as listed below-:
Rainwater tanks : above ground rain storage tanks, below ground storage tanks, garden tanks, above ground full rainwater harvesting systems, graf Carat systems, herkules, top tank,guarantia range,
waterbutts. : names such as rainsaver, rain catcher, cloudburst, oak barrels, raincatcher, garden lake, garden river, blackwall.
Filters and diverters : rainsaver diverter, sankey diverter, raincatcher diverter, optimax filter, patronen filter, minimax filter, universal 3 filter and filter packages, universal filter, wisy, rainus, vf1, vf2, vf3,
Storm attenuation : storm crates, waterloc, marley, wavin plastics,polypipe, geotextile membranes, visquene membranes, membranes, dpm, fleece, terran,vortex, valves, stormwater, management all to compliment our sustainable urban drainage systems range.
Pump packages : eco plus, home pro, graf, 3p technic, karcher, ebara, gardena, irain, power rain, as submersible pumps, pressure pumps or pump control systems, rainwater management.
Hose pipes : hozelock, gardena, kingfisher, hose pipes, leaky pipe, pourus pipe,irrigation,
Thank you for your anticipated business, if you do not find a suitable rainwater harvesting system, rain tank, rainwater filter, storm crate, water butt or if you simply do not find that which you are looking for, then ring me. I will do my best to assist you in your enquiry.
Alistair Tunnington (Managing director)