Rattling or Thumping Pipes – Cures

These cures relate to general rattling or banging when you turn the tap on.

The various reasons for these noises, and their cures are:

Air in Pipes
Typically occurs in new systems, or after some plumbing alterations. You need to purge the air from the system. To do this

  1. Start at the lowest tap or valve and slowly turn on to full. If there is some spluttering leave on until the water runs smoothly then turn off.
  2. Go to the next lowest tap and repeat the procedure, continue working your way around the house until you reach the highest outlet.
  3. Don’t forget outside taps, toilet cisterns and shower heads.

Steam in Pipes
Can affect solar hot water systems and hydronic heating. Generally means the system is running too hot.

  • For solar systems the first thing is to reduce the temperature for the circulation pump start. This will take the hot water from the panels at a lower temperature. If that doesn’t work it may be the storage tank is too small for the area of panels. If you can’t afford a bigger tank shading the panels on summer days can help.
  • For Hydronic heating systems you will need to lower the boiler thermostat.

Insufficient Fixing of Pipes
Affect all sorts of plumbing systems. May need a combination of four different approaches

  • Pack around any loose pipe clips.
  • Install additional clips between existing clips.
  • Install pipe insulation.
  • For pipes in cavities push foam tube insulation along the pipe so it stops the pipe banging on the walls.

If the problem is a bang when you turn the tap off then you need to see the post on Water Hammer.

Rainwater – Pump Size

One of the reasons why most rainwater systems use too much power is because because the pump is too big. For other reasons see Rainwater – Pump Issues

Most pump suppliers and design charts will specify a larger pump than you really need (They sell a more expensive pump, It’s less likely that the pump will be returned because it isn’t big enough, and they aren’t paying the power bill)

If you want to pick the most economic pump here is how to go about it.

Instantaneous Flow

What is the most flow you need at any one time. Here are some figures for typical house fittings.

Fitting Flow Litres/min
Tap 10 to 15
Tap with Flow Restrictor 4 to 6
Low Flow Shower 7 to 9
Washing Machine* 4 to 10
Dishwasher 4 to 6
Toilet 3 to 5
Garden Sprinkler** 10 to 15

*To get to the lower figure you will need to close the supply valve this will add a few minutes to the wash but will help with issues like Water Hammer.

**It’s really better to irrigate the garden with a separate pump.

Add together the highest flow rate fittings that you think you will want to run together, which will give you a Total Flow Rate ‘Q’


You need to aim for a pressure at the fitting of around 150kPa (15m of Head)

To get this pressure you need to:

  1. Measure the height of the furthest fitting above the lowest level in  the tank ‘Hs)
  2. Calculate the Pressure  Loss ‘Hf‘ due to Friction in the pipes See table below
Max Flow Rate
Hf  m head per 100m of pipe
20 25 32 40
12 10.9 3.7 1.2 0.4
24 13.4 3.9 1.3
36 8.3 2.8

The Required Pump Pressure is then calculated from:

Required Pump HeadP‘ m = 15 +Hs + Hf
Required Pump Head ‘P‘ KPa = 150 +(Hs +Hf)) x 10


To order a pump you just need to quote the Total Flow and Required Pump Head


When you are ordering a pump think about getting a Pressure Tank

Water Hammer Cures

If you are getting water hammer in your new house it can be really annoying.

As the problem is caused by fast flowing water being stopped suddenly here are some options to cure it.

Slow the overall speed of flow down

Pressure, which affects the speed of water flow, does vary depending on your location. By turning down valves you will counteract the high pressure and slow the flow down.

These are both no cost options which are worth trying first.

    • To the whole house

If you have got very high pressure at your property you may be able to turn down the external stop tap to the house, while still getting plenty of flow to your taps.

    • To the washing machine and dishwasher

These appliances have separate supply valves which can be turned down. The machines will take a little longer to fill adding a couple of minutes to the wash time………..but how many of us are in that much of a rush!

Don’t stop the flow as fast

Lever action taps are the worst kind of taps for causing water hammer because they can be shut off quickly.

Softer slowing of flow, rather than a sudden stop will reduce water hammer.

These are three options to achieve a softer flow cut off in, listed in order of increasing cost.

    • Slowly turn off  taps.

The no cost option……….but doesn’t always work if you have got children, or just have fast ‘lever action’ taps or mixers.

    • Fit anti- hammer tap valves

These replace the Standard valve inserts with a unit that includes a spring. The spring allows any pressure surge to escape past it and means the tap need more of a turn, and thus longer time, to fully close.

Typically they cost around $6 each plus fitting.

Not  suitable for the more complex mixer units.

    • Fit a surge arrester

This device is fitted to the pipe before the valve. The cylinder  has a piston that separates the water from compressed air in the top.

When the valve shuts some of the water (and the pressure surge) is diverted into the arrester pushing the piston up and compressing the air. It acts a bit like car ‘shockers’ to slow the water flow.

There are several sizes of arrester depending on your system with prices starting at around $70 plus fitting.

Fit a Pressure Reducing Valves

See this link for more information: PRV


See Settling In for more information about when you move into your new house.

See Rattling and Thumping Pipes for more noise problems.


Rainwater – Pump Issues


This photo shows a fairly typical pump installation.

An electric pump with pressure sensor control. It’s even got a fairly large diameter flexible suction hose between the tank and the pump.

So…..What are the issues?

Well water is an incompressible substance so every time some water leaves the system the pressure drops enough to trigger the sensor and the pump starts…………..That happens whether you are having a shower, putting a splash of water on your hands, or even a couple of drops dripping from a slightly leaky toilet valve.

This leads to Three Issues.


Electric pumps are designed to pump efficiently at their designed rate. If you are using water at a slower rate than the design rate the pump wastes energy trying to pump at its designed flow.

A lot more power is used to start the pump then when the pump is running for some time.

A Recent Study for the CSIRO showed that a typical domestic rainwater system used more energy than traditional centralised water treatment and distribution systems.

Pump Life

The main thing that wears pumps out is continually starting rather than running.


Because the pump runs frequently you are more likely to notice the noise. If you have got a leaking tap or toilet valve it will be starting up several times through the night.


If you have got a large block with a slope of several metres it may be possible to install a header tank. This solution however is not normally possible for most of us.

The best solution for the average house is to upgrade by installing a Pressure Tank. Follow the link to find out more.


For more posts about tank water see the Rainwater Section under the Sustainability Tab

West Facing Solar Hot Water System?

If you are committed to sustainability then space on the North facing roof is at premium.

One option may be to look at putting the solar hot water system on a West facing roof.

This will mean you can maximise the space for north facing Photo Voltaic (PV) solar panels.

Although the solar hot water system will not be quite as efficient there are a couple of reasons why it is a worthwhile option.

    • If you check the solar alignment post you will see that its possible to get around 80% of the maximum efficiency compared with a North Facing system.
    • For most families the time when you will be using most hot water is the evening and early morning. The West facing system will have less time to lose heat before use than the North facing system.

I’m not saying West facing is best but it can be a good compromise.


For more Green Ideas see Sustainability


Solar Hot Water

With the current emphasis on building efficiency solar hot water systems are pretty much a standard option if not automatically included.

These systems incorporate either gas or electricity boosting for cloudy days.

Here are a few thoughts on the options for solar hot water:

Split System or Tank On Roof

  • Systems with Tanks on the roof are the most efficient . They don’t need a circulation pump to circulate the hot water to the storage tank and don’t have long pipe runs that lose part of the heat you have collected. If this is the way you decide to go make sure your roof has been designed to take the load.
  • Split systems are easier to service when they go wrong as everything other than the panels is at ground level. Many people also prefer the look as they don’t like the large tank on the roof for aesthetic reasons.

Flat plate or Evacuated Tube Panel

  • Evacuated tube systems are more effective. Also from comments on forums I hear 2mm evacuated tubes are stronger than flat plate collectors in the case of large hail, and are less likely to be hit square-on, due to their shape. Just make sure you aren’t getting cheap quality thinner walled tubes.
  • Modern good quality evacuated tube and flat plate systems should be essentially maintenance-free. Just make sure of the quality, it can cost $300-$400 in labour to replace a defective panel even if the actual panel is replaced under warranty.


Some of the early Solar water systems only insulated the hot water coming from the system. This is poor practice as once the system starts running the water from the storage tank back to the panels warms up. If this cools in the pipes to the panels you will be loosing efficiency. Make sure you have all pipes insulated.

Boosting Systems

  • I think Gas Boosting is probably the best way to go even if you have the higher priced bottle gas rather than mains gas. This is because gas systems only boost the water when you want it rather than electricity where you are heating the whole tank up even if you are only using 10% of the contents.
  • If you `go for electricity its best go for an off peak boosting, but only switch it on if the forecast is for cloudy weather.


See why a West Roof Mounting may be worth thinking about

For more  information on choosing systems for your new house see  ‘Selection / Pre-Start Guide’


Floor Drains

Up until we moved to our current place we have never had floor drains.

Now we have them in bathroom, laundry and the walk in shower. I’m quite impressed and would definitely specify them for another build.

Having had one washing machine overflow in the past I think they are a great idea to give you added security against internal flooding.

So what does it mean if this is the way you want to go?

      • For them to be fully effective the floor needs to slope down to the drain at least 1:80 (13mm in 1m), preferably 1:60 (17mm in 1m).
      • The normal procedure is to cast the slab in the room 25mm below the main slab.
      • A cement grout bed is then laid on the slab, at the appropriate fall to the drain, before waterproofing and tiling.

If you are going to have a walk in shower it can be neater to have a rectangular floor drain like this one.

This example has a stainless steel finish but you can also get covers with a tray that you can fix matching tiles in. All you can then see is a narrow slot.


For similar posts see  Plumbing in the Selection Category.

More plumbing information and 24 pages of Check Lists in the ‘Selection / Pre-Start Guide’


Round or Slimline Tanks?

In addition to the standard round tanks there are a whole range of alternative rainwater storage tanks available.

One popular shape is the slimline tank which will fit in a narrow space. I have even seen a row of them used as a boundary fence.

Before you make a choice it could be worth thinking about finding out if you can find room for a round tank.

Round tanks cost less because they are easier to make and use less material. Typically the cost increase for a slimline tank over a round tank of the same volume is at least 50%.

A comparison from my local Masters store:

  • $800 for a Slimline 3,000 Litre tank
  • $500 for a Round 3,000 Litre tank

If you haven’t the width to fit a 3000L tank you could perhaps look at getting two round 2,000Litre tanks for the same price as the 3,000Litre Slimline tank.

Other advantages of the round tanks are they are a lot stronger, and easier to clean out.


See this post to find out How Much Rainwater Storage You Need


Gas Plumbing

Most people who have mains gas available will have gas connections for hot water and central heating automatically provided by the builder.

But what else do you need to think about?

Meter Location

You will need the meter somewhere where it can be read from the front of the house but is not an eyesore.

Sounds simple but our last builders proposed location was behind a proposed gate that would have been an issue when reading the meter.

Oven and Hob

Our oven and gas hob are together so we have a gas line to that point.

Even if you have all electric cooking it may be worth running a blanked off line to that point if you have an eye on selling the house in the future.

Future Gas Fires

A lot of display houses feature gas log fires.

If you like the idea but can’t afford it now it could be worth getting a gas line put in for the future.

Hot water

If you have thought about the issues with long  Hot Water Pipe Runs you may want a different location to the builders standard for your boiler.

You may even prefer two separate instantaneous hot water units which will affect gas lines.


As previously mentioned in the External Plumbing post its worth considering a mains gas supply to your barbeque if you use it regularly.

What gas plumbing issues concern you?


For similar posts see Plumbing


More plumbing information and 24 pages of Check Lists in the

‘Selection / Pre-Start Guide’