PIPES & FITTINGS OLD - Supadiverta - syphonic rainwater diverter

Go to content

Main menu:


Pipes and fittings - so many choices.

.......... one more reason Supadiverta is such a great choice!


Supadiverta diverts to PVC pressure pipe, PVC DWV pipe, poly pipe or a combination of all three.
References to 1st, 2nd and 3rd priority outlets refers to the outlet’s order of use, the lowest middle flush outlet having 1st priority use and the tallest outlet having 3rd priority use.
The middle (1st) outlet is usually but not exclusively reserved for first flush and continuous sediment extraction.
PVC pressure pipe sizes are nominal and the internal diameters (ID) are larger.
The term faucet refers to a fitting with a female thread, usually at one end only.
The fittings shown are the ones most commonly used with Supadiverta. Other available fittings may provide solutions for less common usage. Hardware stores generally stock higher selling items whereas irrigation stores usually stock the full range.
PVC PIPE AND FITTINGS have low friction loss.
PVC DWV (Drain Waste Vent) PIPE AND FITTINGS are cheaper than pressure pipe and commonly used when diverting long distances.
POLY PIPE AND FITTINGS are cheaper and there are a range of fittings and accessories. 19mm and 25mm low density poly pipe is mainly used by gardeners but many tanks sited away from the house are supplied by larger PN6.3 and PN8 rural poly pipe. This pipe is substantially cheaper than PVC pressure pipe and can be adapted to pressure pipe fittings.
AS/NZS 2032 Installation of PVC pipe systems specifies that PVC-U pressure pipes installed in direct sunlight must be either painted with light coloured water-based paints or otherwise protected.


A 20mm x 20mm male threaded valve socket screws into a SUPADIVERTA 20mm BSP outlet and a (nominal) 20mm PVC class 12 pipe slips into the valve socket’s tapered end. The use of PVC-u pipe cement (solvent) is strongly discouraged for this connection.
The vertical drops connect to either individual horizontal PVC pipes or to a shared pipe.
If using 19mm poly pipe drops, the equivalent poly fitting is a 19mm x 20mm male threaded poly director.

PHOTO 1: Two 20mm PVC vertical drops divert to a 25mm x 20mm reducing elbow and a 25mm x 20mm reducing tee. The elbow and tee are joined by a 25mm PVC pipe (not shown) cut to size.

Supadiverta is designed to use 20mm vertical drops but a larger 25mm x 20mm BSP male valve socket is sometimes connected to the 2nd priority outlet in areas of regular heavy rainfall. A 25mm class 12 pressure pipe (29.7mm ID) has 57% more volume than the 20mm (23.7mm ID) pipe and flow rates can be up to 75% greater. However, the larger pipe is slower to purge and usually takes 6 to 12 seconds but purging can occasionally be delayed for several minutes. During this time, the outlet continues to operate in non syphonic mode and the third priority outlet will immediately purge if water rises above its anti vortex baffle.

If using a 25mm x 20mm valve socket and 25mm pipe, fit only to the second priority outlet and only when diverting to a horizontal pipe.

Do not use the greater volume 25mm class 9 pressure pipe as a vertical drop.

A larger 25mm x 20mm valve socket is sometimes fitted to the second priority outlet. The 25mm drop is shown diverting to a 25mm plain elbow.

25mm and 20mm PVC drops are shown diverting to 40mm fittings. A 40mm x 25mm bush adapts the 25mm drop to the 40mm elbow.

(Two tees are used when two Supadivertas connect to a shared horizontal pipe).

Two 45 degree elbows used to raise or lower a pipe’s height have less turbulence and friction loss than two 90 degree elbows.
A 25mm x 20mm reducing elbow is commonly used to connect a 20mm drop to a 25mm pressure pipe.
A plain tee can be used to make an effective sediment trap in a horizontal pipe. See photos 13 & 14.
A reducing tee can be fitted to a horizontal pipe to fit a connection that attaches to drip hoses for garden watering. See photos 8, 9 and 10.
Bushes fit into PVC fittings, allowing different pipe sizes to connect.

PHOTO 4: Tees, elbows and bushes come in a range of sizes. Tees and elbows are also available as faucet fittings.

Joins two PVC pipes. Reducing joiners are also available for joining different size pipes.

Essentially a joiner that connects a PVC pipe to a male threaded fitting, usually a director or a sprinkler adaptor.

Fits into PVC fittings and connects to a male threaded fitting.

Very useful and are available in some reducing and increasing sizes.
19mm directors and 19mm poly pipe can be used as vertical drops, mainly for garden applications and are often used with PVC faucet fittings to connect PVC pipe to hoses.
Directors are commonly used to connect reinforced pond hose between a PVC pressure pipe and a water tank bottom inlet. The pond hose provides a smooth flow path and serves as a flexible coupling. See PHOTO 10.
A 25mm x 20mm BSP increasing director and a 25mm poly pipe drop are sometimes used on the second priority outlet to substantially increase flow rates. Purging usually takes 6 to 10 seconds but this can occasionally be delayed for several minutes. During this time, the outlet continues to operate with gravity flow and the third priority outlet will immediately purge if water rises above its anti vortex baffle.

Popular with pool owners and gardeners. See PHOTOs 8 and 9.


Available for 13mm, 19mm and 25 mm poly pipe.
Commonly used when a 19mm poly pipe is fitted to the flush outlet to collect sediment. The tap must be fitted to a horizontal length of poly pipe and not to a vertical drop as the trapped sediment will make the tap difficult to open and close. See PHOTO 7

Connects to a PVC faucet fitting and snap fits to a hose connector. See PHOTO 10

Joins a hose to a sprinkler adaptor.

Connects two hoses. Also available as a reducing fitting to connect different size hoses.

Poly directors are also available as increasing and reducing fittings. The ones shown are 19mm, 25mm, 32mm, 40mm and 50mm but other sizes are also available. Also shown is a 40mm director partially fitted to a female threaded elbow. See PHOTO 16
There are numerous threaded poly fittings available.

PHOTO 6: PVC and poly plain & reducing joiners.

45 degree elbows are fitted near the bottom of the drops to allow the horizontal pipe to clear the downpipe. The distance between the elbow and the outlet determines the maximum available head as the elbow will also break the vacuum.

The 45 degree elbows fitted to the 25 mm horizontal pipe minimises friction loss.

Note that the horizontal pipe and fittings are shown above ground for clarity. The pipes are usually buried.

PHOTO 8: Reducing tees can be fitted anywhere along a horizontal pipe’s length to connect to drip hoses.
The plain reducing tee is connected to a 20mm PVC valve by a short PVC pipe. Another short PVC pipe then connects the valve to a faucet socket.
This allows a 20mm BSP male threaded fitting to be screwed to the faucet socket. The sprinkler adaptor shown allows a hose to be connected.

  Photo 9: Neat and compact.

Fitting an elbow allows the pipes to run parallel.

PHOTO 11: Connecting a PVC pressure pipe to a tank’s ball or gate valve is easy.

Screw a director into each end of a UV stabilised reinforced pond hose and then screw one director into the tank inlet and the other to a faucet socket. The faucet socket then slips over the PVC pipe.
The pond hose serves as a flexible coupling and eliminates elbows.
The tank inlet should be a minimum of 100mm above the bottom of the tank at its lowest point and within a 75 degree arc from the pump’s draw outlet.

Neat and tidy.

A DIY sediment trap fitted to a horizontal pipe will remove a large percentage of the bed load.
Bed load travels slowly along a straight length of pipe. By fitting an inverted tee to a straight non turbulent section of pipe and connecting the tee to an elbow, a lot of sediment will fall down the tee. Larger tee branches are more effective.
There are several combinations of fittings that can be used after the bush.
Water harvested to tanks will be much cleaner and the fitting is also popular with pool owners.

DIY sediment trap. (One version).
Fit a plain tee (branch facing downwards) to the horizontal pipe.
Fit two 45 degree or a 90 degree elbow as shown and reduce the elbow outlet with a bush.
Connect the bush to a faucet socket and a director as depicted.
Connect a 19mm or 25mm poly pipe and fit an inline tap to the end.
The smaller poly pipe will flush the captured sediment at high velocity when the tap is opened.

Very compact when fitted.
The poly pipe can be any length. This simple trap works well and the pipe will not block because water has already passed through the Supadiverta 750 micron filter and discharges at a high flow rate.


Selection depends on the total roof area harvested, the regions rainfall pattern and the intended use. For example, there would be little point in connecting a drop to a large horizontal pipe if the drop was supplying a drip hose that required no more than 4 litres per minute.
If plumbing to tanks, it is best to base calculations on a one metre head as this generally represents a half full tank.
The pipe length and all fittings cause friction/flow loss.

CLASS 12 pressure pipes are mass produced and sold at hardware stores and irrigation outlets. Always compare prices.
CLASS 9 pressure pipes have the same outside diameter but thinner walls give a greater internal volume. Rated at 900 kPa but not available in 20mm.
Both pipes use the same pressure fittings and depending on size, class 9 pipes are up to 50% cheaper than class 12 pipes. Class 9 pipes are not as widely available.
Our DVD shows two 2,000 litre tanks supplied by a 32mm pressure pipe diverted to by two Supadivertas harvesting a combined roof area of 84 square metres.
A shared pipe flowing from opposite ends to two tank inlets is very efficient as it substantially increases the pipe’s flow capacity. It also allows more water to divert to a settling tank and allows the infeed pipes to also serve as tank balance pipes.
A larger 40mm class 12 pressure pipe is not much dearer than 32mm pressure pipe. Some fittings are actually cheaper.
Higher volume class 9 pressure pipe generates about 7% higher flow rates than class 12 pipe.


The tanks are buried 80mm and sit on a compacted sand base.
A buried 32mm PVC pipe diverts to the two foreground 25mm & 32mm inlets.
The rear tap attaches to a garden hose to top up the pool.


What is underground?
A 32mm poly director connects to a faucet adaptor and a 32mm reinforced pond hose. A second 32mm director (not shown) connects to the other end of the pond hose and to the elbow fitted to the tank’s inlet. The faucet adaptor is then fitted last to a plain tee fitted to the buried 32mm pipe.
Note that the pond hose is not cut to length.

Very cheap and easy to fit.
A 19mm drop connected to a 25mm poly pipe has good flow rates. For example, a single 19mm drop with a 1 metre head connected to a 13 metre length of 19mm poly pipe connected to a tank bottom inlet will flow at 15 lpm but the same drop will flow at 25 lpm if connected to a 25 mm poly pipe. The poly pipe lengths do not include friction losses through fittings given as pipe length.
A 25mm x 20mm BSP director and 25mm poly pipe is sometimes fitted to a 2nd priority outlet but purging can sometimes be slow.
A 25mm poly pipe drop with a 2 metre head connected to a 25 metre length of 25mm poly pipe will free drain to a pool at 38 lpm. In real life, the heavy rain required to produce this flow rate would normally mean that the pool would not need additional topping up.

Is measured as an inside diameter and can be connected to PVC pressure pipe.
Is easy to lay but care must be taken with larger pipe to ensure that it is laid as level as possible to avoid air locks as the required air flushing velocities are high.
Rural Poly pipe is much cheaper to use for long runs to remote located tanks than PVC pressure pipe. The sizes mostly used with Supadiverta are 1¼”, 1½” and 2” with respective minimum internal diameters of 31.3mm, 37.8mm and 50.5mm.
A downside is that the pipe is sold in long lengths. Finding an outlet that is willing to cut shorter lengths is difficult but the 2” is available in 100 metre coils and the 1½” in 150 metre coils.
PPI Industries manufacture two popular rural poly pipes; Green Stripe and Fat Stripe. The two pipes use different fittings as the higher pressure rated Fat Stripe has thicker walls and a larger outside diameter.

PPI Rural Green. Green Stripe.
Pressure rating: 6.3 PN (630 kPa)
red fittings.

PPI Rural Poly. Fat Stripe.
Pressure rating: 8 PN (800kPa).
green fittings.
This PPI rural poly PDF link includes easy to understand flow rate charts. Note that the calculations assume a straight and level surface.

Blue Stripe poly pipe must not be confused with Rural poly pipe.
Blue stripe has a higher pressure rating and is measured as an outside diameter. The 25mm Blue Line poly pipe commonly used on water tank pressure pumps has an internal diameter of approximately 20.6mm.


Friction losses in pipe fittings are added to the pipe length to represent their equivalent friction loss as metres of pipe. For example, a 5 metre length of 40 mm PVC pipe fitted with two 90 degree elbows will have a total friction loss of the 5 metre pipe plus 2 x 1.3 metres for the two elbows, a total pipe length of 7.6 metres.

Friction loss of PVC fittings shown in equivalent metres of pipe

Size mm


























Back to content | Back to main menu