If you are looking for a way to both conserve water but also have a healthy garden, an Olla might help.
While surface watering, some of the water will be lost to evaporation, and you may not get the soil damp enough to encourage the roots to spread deeper.
This is when the Olla becomes helpful; made from porous clay, this pottery can be filled with water, which it will then gradually seep into the surrounding soil. While most of it is burred, enough of the neck is out of the soil to fill it.
You can make your own for your outdoor garden using terracotta pots and water-proof adhesive. Simply glue two pots together, and fill the hole on one side. When the glue is set, just bury the pots (with the unfilled hole up), fill with water, and cover the hole with a saucer, cork, or rock.
If, however, you only have indoor plants, you have an option, too! You can get terracotta watering spikes that work in a similar way, but a glass bottle fills it.
While they might not be suitable for all plants, for many plants they are suitable, and can help with your gardening chores.
While they might not be suitable for all plants(such as plants that prefer dry soil), for many, they are.
Images from Permaculture Research Institute
(you can also hook these together with drip lines)
EDIT: Gardening with Less Water, David A. Bainbridge (2015)