Talked to a few people in the area. Drought here, some wells are running
dry, some are running into water not fit for consumption at this point.
In regards to a well running dry, its come to my attention that a pump has
no facility for shutting down if there is no water at the head. That is,
continue running and burn up the pump. Is this true?
We use a pressure switch on our well that will shut off, and remain off if
the pressure falls below about 5 psi. A little spring loaded lever on the
side allows you to manually restart the pump when/if that happens.
These switches are pretty common, and cost maybe $20 at the big box.
During normal operation, the pressure remans between the 40 and 60 psi
setpoints. If your pressure tank is precharged to slightly below the low
then the pressure will drop to zero quickly when the well runs dry.
We've had the misfortune of testing the switch repeatedly during this
Can't see myself going to the big box store and asking for a pressure switch
for controlling/disabling the well pump. A pressure switch normally turns
the pump on/off as it is now. Does the disabling switch you're speaking of
fall inline electrically with the switch that turns the pump on and off?
Or, is it actually a dual purpose switch, one for normal activation of the
pump, and for disabling the pump at some low pressure setting?
See model FSG2J21M4 at"
This is just a regular well pressure switch with a low
pressure cut off. They are sold just about any place that carries well
and cost maybe $5 more than the regular switch.
I had to buy a replacement a couple of years ago, think I got it at Ace
IMHO, I would hesitate to trust this type of switch to reliably protect the
pump from damage caused by running dry. I do have this type of switch
installed but mine prevents motor startup if the pressure falls below about
15 lbs. (normal range ~25-50)
The older technology was to use liquid level controls connected to high and
low level electrodes in the well. This system not only protects the pump
from dry running but also prevents a slow recovering well from causing the
pump to cycle rapidly at the low level cutoff and will not allow the pump to
start until the well has filled to the high level electrode. This system
requires an extra set of wires to run inside the well and also a controller
at the panel. This system is not very elegant and the electrodes must be
A more recent technology uses a micro controller circuit board added inside
the normal well controller. This controller senses the drop in electrical
current draw by the motor when the load drops due to running with no load.
This control also has a timer to delay the motor from restarting in order to
give the well time to fill. I do not have a link but your pump supplier
should be able to help, or try Google, IIRC they are marketed with names
like pump sentry or pump saver. These controllers are quite elegant and do
not require added wiring so are quite easy to retrofit to an existing
installation, and do not require pulling the pump. IIRC they cost ~$75.
A large (120 gal) pressure tank may also be something you may want to
Good luck, dropping static levels and low recovery rates are no fun. The
general operating rule is to conserve as much as possible and 'don't get
Thanks for the weblink. Looks very similar to mine, except no bar on the
side. Think I'll stick to using the breaker feeding the switch to keep it
off when working on whatever's downstream electrically from it (pump and
The low pressure cutoff is the ticket in my opinion to protect the pump due
to water unavailability. How would I know if I had a low pressure cutoff
already, and is connected as such to operate that way? Bounce the part
number against the square D catalog is my guess, but doesn't tell me if its
connected properly for disabling the pump due to low pressure.
My pumptrol has decreased its low setting from 45 to 40 psi on its own. The
weblink says low and high cutoffs are easily adjustable. Any idea how these
According to the link, there is a model with an on-off switch, and a
model with the low-pressure cutoff. I've not seen the one with just the
switch, but assume that both have the little lever that sticks out the side.
The one with the low pressure cutoff has a legend engraved in the cover,
something like off/run/start. If you start from the off position (and have
pressure), then you move the lever to the start position. It's spring
so you have to hold it until the cutoff pressure threshold is reached. At
point, you can let go of the lever, and it will remain in the run position.
low pressure cutoff kicks in, the lever pops back to the off position, where
it will remain, until manually moved.
Note that the switches are designed to protect the pump on a well that
occasionally runs dry. They are not designed to, for example, fill a large
storage tank by cycling a weak well. Another poster has mentioned an
electronic device that monitors the pump current, which is used for that
application. It will automatically reset, after a time delay (as the well
To adjust the pressure, remove the cover. You will see two threaded rods,
each running through a spring, with an adjustment nut. Compress the springs
more to increase the pressure. If you cycle the well with the cover off, you
can watch the mechanism to see how it works.
Hershel, with respect, please let me know if I have this right.
- A well is suffering slow recovery.
- The pump turns on when the pressure drops below 40 psi but does not
continue to deliver water because the level is below the pump inlet.
- The pressure tank maintains 40 psi due to the inlet check valve next to
the tank and/or the check/foot valve above the pump.
- The pump continues to run and attempts to pump air.
- The plastic pump impellers (and motor) heat up from lack of lubricant or
- How does a switch that cuts off pump power @ <5psi protect the pump?
- Why would a lack of water in the well cause the pressure in the tank to
drop from 40 psi to <5 psi?
- How much time could elapse before someone turned on a tap and used enough
water to cause the pressure to almost completely drain?
- When the water stops and the ~15 psi of precharge air starts to come out
of the tap what are the chances that the user does not just turn off the tap
and say WTF?
- How much damage has now been done to the pump?
- How much does a pump cost?
- How much trouble/cost to obtain and install a new pump?
This is what I use, on my well, and it turns out to be a good $5 solution
to my problem. I would not suggest that this would be a universial
solution for all wells.
If you were to draw just enough water from the pressure tank, to
turn on the pump, turn the water off, and then have the well run
dry while the tank is filling, then this thing would not turn off
the pump, until the well recovered enough to finish filling the tank.
Your pump would run dry during that period.
This is not something we see with our well (yours could be
different). Our well runs dry when we have the garden hose flowing,
and someone decides to draw a bath (and there is a severe drought).
The pump is running continuously (or almost continuously). If the well
quits producing, the tank loses pressure quickly, since the flow rate
Well pressure tanks (at least all of the new ones I've seen in the last 20
years or so), have a bladder that separates the precharged air from the
water. Our low pressure point (that turns on the pump) is 40 psi, so our
tank is precharged to about 35 psi with the tank empty. If the water
pressure goes below the precharge pressure, then it drops to zero
instantly (because the tank is empty), so it really doesn't make much
difference if the low pressure cut-off is 5 psi or 15 psi. (And the
does not come out the tap).
I should add that we sized our pump for normal conditions (we are in
a severe drought now), and during normal conditions, the pump can
run continuously. I bought a switch with a low pressure cut-off when I
bought the pump, not knowing if I would need it of not (it's like an extra
$5). We probably went for 3-4 years without the pump running dry.
I don't know the impact of "running dry" on pump life. The motor is below
impellers, so it remains submerged, and the motor bearings are sealed.
The impeller bearings are water lubricated though, so they would certainly
As always YMMV and no two wells are the same.
IMHE the pump and motor bearings are water lubricated and not sealed. The
damage to the impellers is caused by dry (usually with sediment acting as an
abrasive) friction inside the plastic pump stages.
IIRC some smaller pressure tanks do have bladders but most larger tanks have
floating discs which help to prevent evaporation and waterlogging but are
not airtight and will allow the precharge air to escape out of the delivery
You are correct that pump sizing is important but most pumps are sized with
a greater than required capacity to compensate for reduced performance as
the pump ages and wears in service.
IMHO the best practice in any limited production well is to place a
restriction fitting (~$5) in line to limit the rate of drawdown. These
restrictors are just a piece of rubber with a hole that restricts the flow,
(the rubber will wear a lot longer than a steel restriction but it will get
bigger in service so should be serviced and replaced periodically). If a
well has a production rate of 5 gpm then a 3 gpm restriction will go a long
way to preventing the well from being pumped too fast and will also be
gentler on the gravel formation carrying the water and will reduce silting
and loss of production rate as silt builds up in the gravel formation around
the well screen. These restrictors are cheap and can be placed next to the
tank to allow easy servicing, I prefer to place them in the well below the
pitless adapter but that is because I have a yard hydrant above the pitless
In my region most wells have limited production and are located in (200'
deep) very thin layers of gravel. If these wells are sucked too hard they
will pick up fine clay silt which builds up around the well screen and
chokes off the flow into the well. The normal course of events is for a new
purchaser to have frequently running sprinklers, followed by green grass,
followed by hauling water, followed by the appearance of a drilling rig, and
often a for sale sign. I have seen wells that have choked off due to the
owners allowing the sprinklers to run overnight only once! Compared with
wells, pumps are cheap and owners should be a lot more careful and worried
about their wells than their pumps.
In order to guaranty that the water level in the well never drops below the
screen (which can be VERY harmful to these limited production wells) it is a
common best practice to locate the pump pickup above the screen in the well.
IMHO, ALL wells of less than unlimited production should be equipped with
Good luck, don't get greedy, and YMMV.
The reservoir/pressure tank here is also bladder type. It legs off the
primary line from the pump. A mutual line from the pump and tank feed the
line to the house and so forth. Its not in series, rather parallel lines,
one from the pump and one from the tank feed the feed line. When the water
pressure is too low, due to water loss/use at the feed line and if the
pressure tank runs too low (happens simultaneously), the pump kicks on.
What about air injection used to diminish hydrogen sulfide gas used on the
primary line coming from the pump? This added air aids an inline unit
downstream on my setup. This going to affect the thing regarding the low
psi pumptroller switch off?
Restrictions mentioned by "Private". Many well owners have filtration
systems built into the water system. Don't these act as restrictions?
Piping itself: I do know that my piping starts at 1 1/4" pipe in the well
house. Changes to 1" to feed a 3 stage filtration system, then drops to
3/4" for feed at entry to plumbing for the house. My irrigation water for
the lawn and so forth are not filtered, but the piping is dropped down from
1 1/4" to 3/4" to the hydrant that feeds the separate garage area and a
hydrant out in front of the house. This 3/4" piping legs off just before
dropping down to the 1" piping to the filtration system. Then there's the
midget tubing the legs off inside the house that each feed the bathtub, one
for each bath sink, and one for the kitchen sink. Aren't these decreases in
piping ID size seen as a restriction upstream?
First of all, I've drank well water all my life, and I design control
neither which makes me an expert on wells !
The restriction is put in place to reduce the pumps capacity. The best thing
is to buy a pump that can't flow faster than your well can produce. This is
simpler said than done, and you well may change, due to a drought, or in
the case if the Texas hill country where I live, a developer puts in 3000
down the road from you.
In short, the restriction must throttle the pump output to do any good. To
that effectively, it has to be in the pump feed line, prior to a connection
tank, or feed line to your house. Otherwise the pump will fill the tank at
flowrate, reguardless of the demand from your house. If you throttle the
to your house, all you do is cause a pressure drop at the house when you
The size of the well pipe is misleading, because it has to have enough
strength to support the weight of the pump, and water column. Your 1 1/4
can support a lot more weight, than a 3/4" pipe would.
Sorry to hear you have hydrogen sulfide gas. I had that problem on a
well. Is your well deep ? The cost of replacing/rebuilding the pump, etc. go
rapidly as the well gets deeper. I used to have a $2500 pump that cost $800
pull. I never worried about running dry, but if that had been a concern, I
have been willing to spend more that an extra $5 to protect the pump ! (I
this was the point that "Private" was making.). I suppect that the air
wouln't have much affect on the cut off pressure, etc. Perhaps the extra air
effectively increase the size of your pressure tank (because the air in the
Don't see major use or effect from possible housing in my area for another 2
or 3 years my central TX area. Other housing development much further west
and north unable to affect my area.
Pump capacity restriction is good for unrestricted use. The best
restriction is the user of the water supply, be it drought or not.
My major drinking water came from Edwards aquifer via S.A. area while
growing up. My supply does not come from there now.
A developer may tap water from a municipal water system in the area in lieu
of incorporation, or drop their own well. Also is a risk if the developer
uses a conglomerate sewage system that puts it wastewater (treated,
filtered, or not) back to its source of water, the well or your well.
A pressure drop occurs with or without a restriction in place when flushing
the toilet as seen by the pumptroller, restriction or not. All a
restriction plate does is restrict the flow and time delay the pressure drop
over a longer length of time as a result. It doesn't matter where or what
the restriction is, whether a restriction plate before the pressure tank or
feed line, a restriction plate further down the feed line, a smaller ID pipe
downstream, a restriction in the line caused by a filter. They all do the
same thing as seen by the pumptroller.
Placing a restrictor plate before the tank reservoir and feed line restricts
the feed/flow from the pump, but does not affect its desired result of
affecting the high side pressure result required by the pumptroller. Just
placing an additional burden on the pump itself with a line restriction is
the only actual effect, decreasing the life of the pump.
1 1/4" pipe can support more flow than 3/4" pipe at the same pressure.
Weight is only important in moving the water up the well, not at ground
level. 3/4" piping is never used from the pump to ground level.
Handling and removing hydrogen sulfide gas is no big deal. Aerate the water
and flush it/burp it, or put it in holding tank and let the gas aerate there
naturally. First is cheap, but wastes water in the flushing, last one is
more expensive at outset.
Well is not deep as wells go in central TX. 550 ft.
replacing/rebuilding the pump, etc. go
My concern is the well running dry at the head of the pump, and the pump
continuing to run.
Air compresses greatly in relation to water. All my concern is for amount
of water in the tank, not any introduced air.
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