Hot water system problem..

I have an electric Reem that only looks a few years old that is suddenly going luke warm/cold after just one shower.

I looked on the net on how to fix, but the most common occurrance is the 'dip stick', which mine doesn't seem to have.
My cold inlet is at the bottom of the HWS, so I'm guessing I don't have a dip stick to replace.

Can anyone shed some light on this problem?

Thank you.
I assume it's a mains pressure unit, not gravity feed? Usually fairly reliable units.
There's not much to go wrong with them. Thermostat or element would be my guess.
Time to call a plumber. Should be a cheap fix.

I had a Rheem, main element used to die regularly, every 3 years or so.

If you have a twin element then this is actually heating the water and it does not heat up the whole lot, just a bit up the top. This is why you get one shower then cool water.

New element required $$$$$:(
Jeremy, I think you need an electrician (not a plumber) if the problem is electric elements & thermostats (and I agree with the others, I think it is).
Yep, what Macca said. And you need an electrician, not a plumber, unless it's leaking that is.

If it's a twin element (upper and lower) HWS, the lower element heats the main body of water in the tank overnight @ off peak rate:), giving a full tank of HW.

The upper element is wired in a way that makes it cut in (at the peak rate:() anytime the the hot water reduces to a small amount, above the upper element. This is to ensure that you don't completely run out of HW. It also means that you only get a few mins of HW, until it reheats the top QTR of the HWS.