I have a small cottage/cabin (26' x 24'), small budget, where living
for weekends and vacation, 2 adults. I did the construction myself
(extending a 10'x10' existing one).
There is not a septic installation; so far the toilet is outside, also
I made myself an outside shower.
There is not running water, only rain water or bring water from a
spring (when not raining). I am collecting water into a 250 gal water
tank.
I am thinking to have an inside toilet and a shower. I did prevue a
separate room for that. I would like to use these facilities during
the winter also, (ski season), when frequently -20 C.
What would be the solution to have an inside toilet and shower? There
is also a boiler for hot water.
Is a septic fosse a good solution if not having running water? Any
other solution?

Thank you,
Chris