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How to control water tanks placed at different height levels?

Updated: Jun 30, 2023

Many water tanks being supplied by single pump is very common in India. How water tanks are placed overhead, with respect to each other creates two scenarios. First scenario, water tanks are placed at different height with respect to each other, with one tank at top. We shall call this scenario TOP-1+. Second scenario, all water tanks are placed at same level with respect to each other (like on same roof), we will call this scenario All-in-1. Here we focus on TOP-1+ water tank scenario and explain how alarm/automation can be used to control all the water tanks.

Water Tanks at different height levels with gate valve controlled inlets
Water Tanks at different height levels with gate valve controlled inlets

Top-1+ Initial State may look like as in diagram, with water tanks placed at different height level, connected to same water delivery pipe coming from one pump. At most sites, gate valves may in place to control water supply to each water tank. At some sites non-return (NR) valve may be there as shown in diagram. To make site ready, there are two ways. One is using the siphon technique and second is by linking the inlet and outlet of water tank. The purpose is to use delivery pipe to get water from top tank to lower tanks.

Water Tanks at different height levels with float valve controlled inlets
Water Tanks at different height levels with float valve controlled inlets

Using Siphon Technique requires

  1. All gate valves to be open at all times

  2. Non return valve must be in place to stop back flow of water

  3. Ball cocks are fitted inside lower level tanks control water inflow

  4. A siphon is installed inside top water tank using by connecting pipe down into water tank shown in image. How much down has to decided at site knowing that siphon will suck water from top tank till the suction end of siphon.

Water Tanks at different height levels With Inlet -Outlet Joining
Water Tanks at different height levels With Inlet -Outlet Joining

Using Inlet Outlet Link requires 1, 2, & 3 as required for siphon technique. The only difference is that here water will be withdrawn from top tank (for lower tanks) from its water outlet pipe as shown in image. This technique is useful when it is difficult to install siphon inside water tank.


Why we are taking water from top tank for lower water tanks by using siphon or inlet-outlet link? Because when the motor is not running the lower level tanks will get water from top tank, and when top tank level goes down it will get water from pump, which will be started when water tank level falls below low level water sensor placed in water tank. So top water tank level becomes the only water tank level which need to be controlled to control water storage level in all water tanks connected to water pump. Please note, all the water tanks excepting top tank, shall always remain full as long as top water tank have water available in it.


With above readiness, we are good to go for water level alarm or water pump automation. In this type of water storage system it is important to keep top water tank filled, so we recommend using water tank alarm for overflow alarm as well as low water level alarm. For best results or fully automatic water pump control is advised.

Water Tanks at different height levels With Siphon Use
Water Tanks at different height levels With Siphon Use

With full tank level water sensor and low water tank level sensor in water tank as shown in diagram, we can be sure that there shall be no overflow and also there can not be any water shortage concerns. For large housing complexes, societies and industries fully automatic water level controls are best to maintain 24x7 water supply without any human attention.


SensaSwitch offers fully automatic water pump controls for all type of water pumps including small single phase (220 volts) switch / starter operated pumps and for heavy duty 3 phase (440 volts) pump sets DoL/SD starter operated pump sets.


Out of the two methods explained above to control water tanks at different height levels, the inlet-outlet joining of top tank should be preferred as it offers greater reliability. Also as inlet and outlet are easily accessible it is easier for plumbing work, but yes it will require plumber to do it. On the other hand installing is siphon is very easy as only some additional pipe has to put inside water tank to suck water (it can be plastic pipe as well, tightly clamped on inlet). But as it has to installed inside water tank, inlet inside water tank should be easily accessible. Major downside of a siphon is that if any air enters due to loose joint, the siphon will fail.


If above is good enough for your site then its time to use best of tech to save water and electricity. In case there are still any issues which needs to be resolved, remain assured there are many more tools and techniques to get the results at site. We shall be happy to answer any such concerns, free of charge.

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