water tank and filter question

[Oiler]

i am getting a new water tank and filter system installed on a new house.

 

just curious as the filter guy says its better to have the filter after the tank (and before the pump), then into the house because he says it will filter a bit better..

 

BUT, my question is, does this affect the water pressure instead? to me it would seem that having the filter before the tank would allow the pump to suck water more easily and have the added pressure from the tank. only asking as we are installing a rain shower and would like more water pressure in the showers.

also, i know how gross the tank will get with this crappy water sitting in it for years.

 

yes yes, i know..... ask him. we did, but he insists on filter after the tank.

 

extra info. its a 1000L tank. the filter system is the big canister type. about 1.5m tall. and then a bonus smaller canister after, about 0.4-0.5m tall.

[bankruatsteve]

What will the filters be filtering?  It would seem better to put them in front of the tank for most cases unless good pressure is needed and not available.

[VocalNeal]

There maybe some logic but better filtering is not it. Thai contractor? read "It is easier for me"

 

Most domestic water pumps have a max of 9m lift. So if the tank is 2m high this equals 11m of head about 15 psi on old money. This does not effect the discharge pressure. 

 

Most domestic water pumps have the same discharge head but bigger pumps have a higher capacity. Rain shower should be OK a waterfall one might require one size bigger pump.

[KhunBENQ]

We have a 255 watt pump and a simple sediment filter after the tank and before the pump.

More than enough pressure in the second floor.

Our pump has a small pressure tank attached. Highly recommended.

Less cycling of the pump.

Or even better a separate pressure tank (and pump without).

 

Filtering before the tank does not harm but I doubt it makes much sense.

Tank will always develop some "filth" on the ground.

 

Is your tank elevated on a rack?

[scorecard]

I'm aware of putting the filter before the pump in a scenario where the water is very dirty so that the dirt, parts of leaves etc., don't block the pump, damage bearings etc.

 

But perhaps in that actual scenario there's a case for two filters, the first one before the pump to remove bigger items. 

[Fruit Trader]

Note. If a filter is placed before a pump unnoticed cavitation can occur if the filter clogs and begins to restrict flow.

 

The OP makes no mention of supply type, why it requires filtration or if its a combined city water pump with tank backup or a stand alone pump and tank.

[tifino]

 the chicken before the egg thingie could be easier to wade through; if OP @Oiler puts up photos of what he'd dealing with! - especially the filter.

 

but at the moment, to me, it seems a tank for collecting rainwater, and the pump to help distribute?

[grollies]

1 hour ago, Fruit Trader said:

Note. If a filter is placed before a pump unnoticed cavitation can occur if the filter clogs and begins to restrict flow.

.....is the correct answer.

 

Filter before the tank or after the pump.

[Oiler]

thanks all for the replies

 

ended up putting the filter before the tank. we will see how it works out.

 

its city/town water. not a well or rainwater

[Yellowtail]

I think the filter is generally after the tank as the tank works as a large sediment bowl with a lot of crap settling out without clogging the filter.

 

I like the filter before the pump to protect the pump and facilitate constant pressure.

[grollies]

On 1/26/2019 at 11:52 PM, Yellowtail said:

 

I like the filter before the pump to protect the pump and facilitate constant pressure.

It won't 'facilitate constant pressure' if your filter starts to clog. See Fruit Trader's post #6.

 

[Yellowtail]

4 hours ago, grollies said:

It won't 'facilitate constant pressure' if your filter starts to clog. See Fruit Trader's post #6.

 

Nor if a pipe breaks.

[TravelerEastWest]

Tanks for sure get sediment which needs to be cleaned out...

[grollies]

One thing I haven't read on the borehole threads is how the borehole pump is controlled.

 

A simple floating ballcock and pressure switch arrangement is not suitable on a submersible pump as the pump will cycle on and off repeatedly which they are not designed to do.

 

You can manually fill your tank or have a float switch connected to an actuated valve. This arrangement lets the tank empty to say 25% before the actuated valve opens, the pressure switch activates and the borehole submersible starts. The pump will run until the float switch activates and closes the actuated valve and the pump stops. No repeated cycling this way.

[Fruit Trader]

16 hours ago, grollies said:

One thing I haven't read on the borehole threads is how the borehole pump is controlled.

Two common methods.

 

1. A tank float switch controls power to the well pump. This can be direct or via a contactor. On off differential can be adjustable depending on float switch type.

 

2. Pump is controlled by pressure switch and bladder tank combination which directly feeds the house.

[grollies]

27 minutes ago, Fruit Trader said:

Two common methods.

 

1. A tank float switch controls power to the well pump. This can be direct or via a contactor. On off differential can be adjustable depending on float switch type.

 

2. Pump is controlled by pressure switch and bladder tank combination which directly feeds the house.

Which is fine if you are only feeding a single tank or a couple of tanks commoned-up.

 

If filling multiple tanks in different locations as I do, from a single borehole, you'll need float switches and actuated valves and a pressure switch to control tank levels....unless you do it manually...

[Fruit Trader]

55 minutes ago, grollies said:

Which is fine if you are only feeding a single tank or a couple of tanks commoned-up.

 

If filling multiple tanks in different locations as I do, from a single borehole, you'll need float switches and actuated valves and a pressure switch to control tank levels....unless you do it manually...

That depends how far apart the tanks are and the difference in levels. On the farm we supply multiple tanks from a common  well tank using a .75 HP constant pressure pump with ball valves at the remote tanks. One of the tanks is gravity feed only.

 

We could of course use high capacity bladder tank and feed it all from the well pump only. 

[grollies]

1 hour ago, Fruit Trader said:

That depends how far apart the tanks are and the difference in levels. On the farm we supply multiple tanks from a common  well tank using a .75 HP constant pressure pump with ball valves at the remote tanks. One of the tanks is gravity feed only.

 

We could of course use high capacity bladder tank and feed it all from the well pump only. 

Agreed, I was speaking specifically around submersible pumps.

[Fruit Trader]

On 2/6/2019 at 1:21 PM, grollies said:

Agreed, I was speaking specifically around submersible pumps.

[grollies]

26 minutes ago, Fruit Trader said:

Don't agree. At B1,100 for an actuted valve and float switch  with a standard tank is a lot cheaper than buying a bladder tank.

 

And you are using the submersible to pressurize the tank?

 

Don't know much about how the bladder tank works but the submersible should pump to an open end.

 

I take it the bladder tank does away with the house pump?

 

That means your submersible pump is cycling often to repressurize the tank rather than just refilling a standard tank once or twice a day?

 

 

[Fruit Trader]

2 hours ago, grollies said:

Don't agree. At B1,100 for an actuted valve and float switch  with a standard tank is a lot cheaper than buying a bladder tank.

 

And you are using the submersible to pressurize the tank?

 

Don't know much about how the bladder tank works but the submersible should pump to an open end.

 

I take it the bladder tank does away with the house pump?

 

That means your submersible pump is cycling often to repressurize the tank rather than just refilling a standard tank once or twice a day?

 

 

I have two Festo 3/4 diaphragm valves on our washer conveyor to control dip level. Cheap Chinese valves are around 900B a pop, quality valves with spares readily available are 4000B +. Using them to auto fill a tank would also require float switch, power supply etc.

 

Bladder tank and pressure control on multi stage submersible well pumps is a common arrangement.

A little video to help grasp the idea of using well pump and pressure control to provide a service that does not cycle its pump at an undesirable rate.

 

Reminder for this quote - Filling multiple tanks from one well pump.

 

 

 

[cooked]

As someone that is about to install a new tank, I reckon a pre-filter followed by an additional filter before the pump makes sense. If pressure is reduced, time to clean the filters.

[grollies]

40 minutes ago, cooked said:

As someone that is about to install a new tank, I reckon a pre-filter followed by an additional filter before the pump makes sense. If pressure is reduced, time to clean the filters.

Water filter after the pump, not before it. Restricting flow to the pump will only cause it to cavitate.

 

Pumps push far better than they pull.