odd that you pay the water bill, but your landlord reads the meter or somehow knows your usage.
Do you get the bill via the landlord or does it come directly to you?
There is a curbside meter somewhere. Make sure you have no water going in the house or outdoor spigots, and go check the meter. You will need to watch it for a moment or two. It should not be turning. Not at all.
FWIW, there's two of us here, and we consume approximately 500 ft3/month (9 gal/ft3) an amount that I consider high but not excessive.
We have about 660 SFR users in our district, and consumption varies wildly dependent on consumer's 'water habits', so your landlord saying that you are big consumers is poppycock if it is only based on the consumption of some small # of users with whose meters he is familiar with. Nonethe less, he is probably simply making an observation and means no harm/is not condemning you.
I administer a small water district. Leaks are common. We adjust the bill to the previous 12 month average upon request.
Just so you 'know', check for a small leak. Check your toilets, too. One of them could be steadily over-filling.