Frequently Asked Questions

What is a bore?

So much jargon, what does it all mean?

We will briefly explain some of the terms that are specific to bores, pumps and water that you may not be familiar with.

Bore and Casing specific

Groundwater, water table, aquifer: These all refer to water that is below the surface. How it got there and how long it has been there is sometimes unknown. Sometimes, groundwater can be 1-2m below the surface, other times 300m or more. Water bore drilling aims to provide access to this groundwater and allow it to be brought(pumped) to the surface.

How much groundwater exists under your property is unknown by drillers and geotechnical experts. Only with years of experience and accurate record keeping can we recommend a likely flow rate tailored to your location.

Casing: The main aim of casing is to allow water to flow into the bore and to prevent other particles (sand, clays, rocks) from entering. Bores require a strong walled tube from the water to the surface to stop the open hole from collapsing and destroying the bore and to allow access to water. The most common type of modern bore casing is made from PVC and is 100mm – 150mm in diameter with an electric pump attached.

Steel is sometimes used as bore casing but usually only for very deep bores (>60m) or for production (irrigation) bores (>200mm dia)

PVC Casing comes in 2 different parts, slotted and plain. Slotted casing has cuts or slots, cut into the casing to let the water in. Sometimes these slots need to be very fine width(0.5mm or less) to stop fine sand (Andergrove, Bucasia). Other areas can have 5mm to 10mm slots to let the water in.

Plain casing is used from above the water bearing material to the surface to allow access to the water and stop any surface contaminants (rocks, soil, sand, leaves, animals, pesticides) from entering the groundwater.

Screens: An alternative to slotted casing is a screen. Screens are wire wound mesh and vary in length and diameter. They also have different slot sizes to allow water in and keep sand and rocks out. A 200mm dia production well, for example would have 3m to 6m of screen in the water table and usually a 2 or 3mm aperture.

Spears: An example of a smaller screen installation is often called a spear. Spears usually have a 600mm long x 50mm dia screen screwed to the bottom of a 40 or 50mm dia steel or galvanised steel pipe. This pipe is direct buried in the ground is is a permanent installation. The pump is attached to the top of the pipe and special vacuum bilge pumps are required to prime the pump.

For many reasons, spears are much less reliable than PVC bores and are more expensive to install due to the cost of the steel pipe and screen. Spears will always rust and because they operate as a vacuum, the smallest rust hole will render the whole installation inoperable and a new bore will need to be drilled as a replacement.

Yield: Bores are(should be) tested by the driller to determine the flow rate they can sustain while being pumped. Bore yield is usually measured in litres per second (L/s), litres per minute (L/min) or gallons per hour (gph).

Roughly 800gph = 60L/min = 1L/s

Divining, witching or dowsing: A method some people use to "locate" groundwater using wires, branches or twigs. It is akin to religion, those who believe in it will swear by it using faith and those who do not believe will use the lack of peer reviewed scientific papers and studies to debunk it.

It doesn't work for us, but luckily we don't need to divine for water because we have a very extensive database of bores and thousands of test holes to confirm our recommendations at your location.

Some Initialisms

TD: Total Depth or Target Depth. The depth from the surface or top of the casing to the very bottom of the hole or cased bore.

SWL: Standing Water Level. The depth from the surface or top of the casing to the water table when no pumping is occurring.

DD: Draw Down. The depth from the surface or top of the casing to the water level when the bore is being test pumped. The draw down is usually the deepest level the water reached at a specific flow rate.

DP: Development Permit. A permit issued by DRDMW to allow commercial entities to take groundwater for a specific purpose.

Pumps and water flow specific

Surface Pump: Any of the multiple varieties of pumps that live on the surface as opposed to a submersible that lives underwater.

Surface pumps vary greatly in their physical size, motor wattage, flow rates and their pressure delivery. the most common brands of surface pumps are DAB (green), Davey (yellow) and Onga (blue).

Suction Pump (surface): The most common type of pump around Mackay is the suction pump. This is a pump that is installed on the surface and has a single pipe that goes down inside the bore casing to the water table. The pump uses suction (like a straw in a drink) to suck water from the SWL(standing water level) and deliver it at pressure to the outlets.

Suction pumps are no longer useful when the DD(draw down) reaches approximately 7.8m. A deep well injector or submersible will be required if the drawdown reaches that depth.

Suction pumps are usually less than 2200W and deliver a maximum of about 90L/min. They range in price from $200 (Bunnings special) to $2400 for a 45kg pump that delivers 70L/min at 70psi.

Jet Pump (surface): Usually means a Deep Well Injector pump (see below) but people have their own ideas. The "Jet" is the special venturi injector at the bottom of the bore.

Deep Well Injector Pump (surface): Has 2 pipes going down a bore casing, and at the bottom is a special venturi injector. Also called Jet pumps, these pump installations are usually only for bores where the SWL and/or DD are deeper than 7.8m as they are much more expensive than a suction pump and use more power for bores where the DD is less than 7.8m .

The 2 pipes are slightly different sizes, and some of the water delivered to the surface gets recycled back down the poly pipes to feed the injector. The injector takes high pressure - low flow water in from the pump on the smaller poly pipe, and delivers lower pressure - higher flow up the larger poly pipe to the outlets.

Submersible Pump: Subs come in many different sizes from 2" (50mm) dia to 8" (200mm) dia and everything in between. They live submersed under water and push water up to the surface. It takes less energy (watts) to push water compared to sucking it from the surface so subs are usually lower wattage and higher flow compared to surface pumps.

Priming or Prime a Pump: Surface pumps almost always require priming. This is a method of filling the entire length of the poly pipe(s) from the bottom of the bore to the pump inlet with water so the surface pump can suck water, not air. Very few surface pumps are self-priming.

We have a video showing different methods to prime a surface pump, but the most reliable method is the windmill method.

Foot Valve or Check Valve: A one-way valve that is at the bottom of the poly pipe down a bore casing. It only allows water to flow one way, up the pipe towards the pump. When the pump turns off, the FV stops the water from draining completely out of the poly pipe. If the water drains out of the poly pipe, the pump setup will need to be primed again before use.

Pressure Switch: A device that automatically turns the pump on and off based on the pressure in the pump bowl or outlet poly pipe. It is usually mounted on the side of the pump bowl and is connected to the pump by a wire. Pressure switches and sandy bores are problematic, and many pumps have been damaged by the design flaws inherent to standard pressure switches.

Pressure Controller: An electronic device (usually with a digital display) that automatically turns the pump on and off based on the pressure and flow (or lack thereof) of water flowing through the controller. Pressure controllers are a much better and more reliable solution where sand is an issue.

Pressure controllers have 2 very important in-built safety measures: zero flow cut off and over current cut off. These measures protect your pump from further damage.

The main difference between controllers and switches is that water usually flows through a controller and it can monitor the pressure and detect a lack of flow and monitor the current use of the pump. Pressure switches cannot provide either of these benefits, so we prefer all new pump installations (surface or submersible) to have pressure controllers.

Pressure Gauge: A device that shows the pressure in the pump bowl or going through a controller. It is either mounted on the pump bowl or outlet poly line or is inside the controller and measures the water pressure in PSI or Bar.

Head: The height of water in metres. Head is the same as pressure but measured in metres of water (or Bar) instead of psi. Every 10m of head equals 15psi.

How much does drilling a bore typically cost?

Do I need a permit / licence / permission before drilling?

Why should I use a licensed driller?

How long does it typically take to drill a bore?

Do I need a driller to come over and look at the site and provide a quote?

What size casing is supplied?

Where can I put a bore in my yard?

What utilities do I need to search for in preparation for drilling?

What does the homeowner need to do to prepare the drilling site?

Will the drilling rig fit in my yard?

Do you use toxic chemicals while drilling?

How can I see what days/times you are available to drill?

Do you accept credit cards and direct bank transfer?

Can you drill in South Mackay, East Mackay, Ooralea, Bakers Creek, Walkerston, etc.?

Do you drill outside of the Mackay area?

Does Backyard Bores do divining, witching or dowsing for water?