Buyer’s Guide to Water PumpsWater Pumps
Need to buy a water pump? Check out our buyer’s guide to Water Pumps first.
Water pumps, transfer pumps, trash pumps, fire-fighting pumps…the world of water pumps isn’t as easy it might first appear.
So why are there so many water pumps to choose from? The fact is there are many different situations in which you might need to pump water, and each one comes with various challenges. Whether you’re draining a pond or your basement, or want to clear larger areas on a farm or worksite, protect your home from fire, each different type of water pump is designed to make your specific task easier.
What is a water pump?
At its core, a water pump is designed to do one very simply thing: move large amounts of water from one place to another. As time’s gone on, some good manufacturers have designed extremely efficient and durable pumps, so you can count on them when you need.
There are two main types of portable water pumps: electric powered and petrol/diesel powered.
Electric Water Pumps
The most common type of Electric Water Pumps are used for indoor smaller requirements; Rain water tank pumps, small garden pumps, aquariums, caravan pumps etc. Most can be plugged into your standard household mains power or 12 volt power source. They are typically designed for the DIY user for smaller domestic tasks, are often less powerful and require less maintenance than petrol/diesel pumps as there’s no need to worry about changing oil and so on. Then are larger electric pumps (often three phase) for moving water over significant distances – these are often stationary water pumps.
These types of water pump have the obvious disadvantage that you are restricted to use where there’s mains power and have to be connected (unless you use a generator). So they might not be the best fit for many portable uses including common farm/rural applications, unpowered worksites or on your property when there is a blackout.
Petrol and Diesel Powered Water Pumps
The majority of portable pumps used on large properties, in farming, construction and mining and by professional contractors are powered by petrol or diesel, with a centrifugal design. A rotating impeller draws water from the pump and pressurises the flow of the discharge. Petrol or diesel powered pumps produce carbon monoxide emissions, so they absolutely must be used outdoors and are ideal for use on jobsites and for irrigation on a farm / large properties. They start just like your lawn mower; add fuel and oil, pull the recoil chord (or elec start for some models) and the engine is running ready to prime for pumping. There are many types of petrol/diesel water pumps that fall into this category, the main ones including:
Water transfer pumps: Dewatering pumps or “gushers” can transfer high volumes of water at relatively low pressure. Ideal for flood irrigation, fast fill tanker applications, and dewatering of construction sites. Essentially moving large volumes of water from one place to another.
Fire fighting pumps: Pumps with higher pressure so it can pump water from your water source (creek, tank, dam, pool etc.) and discharge with pressure. Ideal for firefighting, fire preparation, high pressure water transfer, spray irrigation, high pressure spraying, wash down and more.
Trash pumps: Pumps that can move water with debris and solids. Ideal for pumping muddy, mucky water on construction sites. For seriously thick sludge water, you may need a Diaphragm pump which works more like a vacuum.
5 key things to consider in a portable water pump for sale:
1. Flow Rate: When it comes to buying a water pump, you need to know how quickly it’s going to get the job done. The number you’re looking for is litres of water per minute. Some portable water pumps can move as much as 2500 litres of water per minute (and above) – more than enough grunt for jobsites and farms before having to consider larger sized stationary pump. For home use, you might only need a 100 -200 litres per minute pump.
2. Inlet size: This consideration goes hand in hand with Flow Rate. Portable pumps generally have an inlet size ranging in size from 1″ – 6″ (sometimes more). Irrespective of the size, centrifugal pumps work the same way; sucking in water through an inlet valve and then ejecting it from a discharge valve. So the difference in size just means that larger pumps can get the job done faster; For example, if you need to empty a pond, any size pump will get the job done, but a 4″ transfer pump will finish a job 4 times faster than a 1″ transfer pump.
3. Maximum Head and Pressure: What is Maximum Head? It refers to the maximum height the pump can pump to (its a specification each pump manufacturer publishes for all their pump model and it is a combination of the suction height and pumping height). If you have a pump with a maximum head of 60 metres, your flow rate will be about zero at 60 metres of head. So, the flow rate diminishes with the height. Overall, you will want to choose a pump that has a max head higher than the height you need to pump. Charts are important to consider (see below) when choosing a pump, because again, delivery capacity falls away as max head capacity is approached.
As a handy rule of thumb, using the Maximum Head capacity of the pump will tell you what the pump can do in terms of; suction height + uplift. For example, if you needed to draw up water 2 metres from the water source to the pump, then move the water from the pump up a gradient of 25 metres, then you would need a pump with a maximum head greater than 27 metres (2 + 25). Also note that as water moves through the hosing and the bends it will encounter friction, causing some small additional head loss – another reason to choose a pump with maximum head larger than your height pumping requirements.
So then also worth considering is; at what pressure do you need the water to be discharged? If you need some pressure for fire fighting, water sprinkling etc., then you’ll need to consider the pumps pressure rating (PSI). To work that out, you look at the pump’s Max Head metre rating (detailed in the pump’s specs); approximately 1 metre of max head is equal to 1.42 PSI. So you can simply multiply the maximum head of the pump by 1.42 to give you the max psi rating of that pump. For example, if a pump has a maximum head of 40 metres, then its max pressure is approx. 57 PSI. As a point of reference, a typical garden hose dispenses water at about 30-40PSI. Generally speaking, Transfer Pumps will have lower PSI capacity, but can move larger volumes of water (higher flow rates), whereas High Pressure Fire Fighting Pumps will have a higher PSI but move lower water flow rate volumes on a litres per minute measure.
NOTE: for full Pump Curves plotting the specs of Maximum Head and Flow Rate for the Water Master Pump range, CLICK HERE – This will help you decide what pump suits your flow and pressure requirements.
4. Type of water pumped: What type of water do you need to move? Transfer pumps or Fire Fighting Pumps are fine for clear water. If it contains debris or solids, you’ll need a trash pump; these are quite common on construction sites. For sewage water or thick sludge you may need a diaphragm pump. If you want to pump agricultural or industrial chemicals, consider a chemical pump.
5. Pump Quality: Firstly consider the quality of the brand’s pump and its componentry such as the engine/motor. Quite often, pumps are used for tasks in your business, for important things such as home protection from fire danger or for life on the farm; so you really want a pump that is dependable and can handle your watering demands. In which case, you’ll want to look for a brand that offers a solid warranty and has a national service network that will look after you if any servicing or repair is required. Check out Water Master Pumps, which come with a two year warranty, are powered by Honda and Yamaha engines and have hundreds of accredited service agents around the country.
Check out our blog for more advice and information on water pumps and check out our specific pump buyer’s guides for:
DISCLAIMER* Please note, this advice is general in nature and we strongly recommend consulting the product manual and where relevant, a professional installer.