Well issues, losing water overnight

With a significant sediment issue I can recommend (happy user, not in any way connected) a type of filter that spins out the bulk of sediment by a vortex action to a reservoir where it can be removed (by opening a valve) without needing to change the actual filter element, (which in my case is a washable screen element) at least as a pre-filter before any other sort of filter that could get clogged up. "Spin Out" or "Spin Down" are reasonable search terms to find that type of filter.

A two-wire 240V pump is normally just wired with 2 wires carrying 240V (+ a grounding wire) - using two wires does not mean it's running on 120V unless you measured the voltage at 120V, and in that case it had better be a 120V pump (unlikely with a 3/4 horsepower, possible with a 1/2 horsepower) or someone did something wrong. One possible thing someone did wrong was specifying the pump that you replaced with "the exact same model" in the first place - its obviously not the original pump if there's a 3-wire pump control box hanging around. There are many variations in pumps and the related pump curves - yours may not be ideal, or else you really are overdrawing the well (assuming a 6" casing [you didn't specify] and 10 foot static depth, with a pump set at 280 ft, you should have ~400 gallons of reserve capacity, which seems like it should be plenty.)

Looking at the timing of the question, you may have already solved your issue(s), but in the event that you didn't, here's a few tips.

1) Water systems are meant to be used, even if it involves kids who like long showers. I personally like a nice long, hot shower, so in our situation it would have been a test of self-control. Besides, who would purchase a 2-ton truck and be told that you could only put 300lbs in it? Plus, the previous answer estimated 15 litres a minute for a shower - that's a lot more water than any shower I have used. In the U.S., most shower heads limit the flow to under 2 gallons per minute (gpm), which would equate to roughly less than 8 litres per minute.

2) Could be the pump, but the impact of that would be felt much more rapidly. It would probably start to show as soon as the pressure tank lost it's capacity on about the first shower.

3) The sediment is probably coming from exhausting the capacity of your well. I picture the pump sucking water out of the water table until it starts running dry and then getting sediment from the empty cavity. Overnight the well replenishes itself and fills the pressure tank.

What will solve almost all of your problems is a reserve tank, sometime called a cistern. This is just a big poly tank of roughly 1000 gallons, that acts as your main water source. The existing pump supplies the reserve tank with a capacity switch that turns on when it reaches a low level and a separate surface pump supplies your current pressure tank. This will put a lot less strain on your well, well pump and provide constant water supply to your house. It will also make it easier to filter the sediment.

If you are able to change out a well pump at 280', then you can install a reserve tank and surface pump. It's not a complex task and you can save a lot of money by doing it yourself. I built a small shed around the tank to dress it up a bit, leaving enough room for the surface pump and a shelf of replacement filters. The surface pump should be available at the same location you purchased the other pump.

My neighbor also installed a reserve tank and put in two pressure tanks, as he wanted the pressure to remain more constant while he was using it. In any event, this should solve all of your capacity issues and make filtering a lot easier.

Several things:

1. Re-train the kids to a 3 minute shower: (Australia uses shower timers and so do showers in swimming pools etc) A shower should be get wet, water off soap on, then rinse off... Not a 20 minute marathon...

2. Why give the motor 120V when it is designed for 240V? Have you checked the voltage being delivered?

3. The lowering of the water level may have put the intake in a "dirtier" position, so you should check.

If, back in 2012, there were only 2 of you, then the water use has increased from say 400 litres to 1200 litres per day, assuming 200 litres per person.

If you think of a shower at 15 litres a minute, then a 3 minute shower is 45 litres but a 20 minute shower is 300 litres then multiplied by 4 kids 1200 litres just for showers without the rest of the use.