If this is possible you are very fortunate. Keep in mind that multiple trips between the plants and water source can become burdensome, let alone messy, time consuming and tiring. Another consideration which all should strive for is collection of rainwater. This is not a constant supply for most regions, but it is ecologically sound and plants like the taste of rainwater more than tap water. Watering the plants is only half of the consideration though.
Drainage is a serious issue when one is confined to a small space.
If the garden is on a terrace, balcony, sundeck etc., make sure the drain water does not affect you neighbors. Also, if you choose a rooftop location, make sure the water can drain off the roof and that there is no risk of drainwater leaking into the penthouse apartment. Causing structural damage to the building is a sure way of being forced to relocate the garden. Ideally, it may be possible to collect the runoff water and reuse it, which would be a sound ecological practice. In any case, if the water drains away through pipes, which are part of the building, it is essential to make sure that solid material from the plants and soil does not accumulate and clog the drainpipes.