During this time many Orthodox Christian will take from the Church bottles of Holy water to be used throughout the year. It is common for the priest to come to the home during this period to bless the home with Water that has been consecrated on the day of Theophany. Here are some thoughts on the value of Holy Water by Saint John of San Francisco.
On Theophany, the Day of the Lord's Baptism, every year a great miracle is performed. The Holy Spirit, coming down upon the water, changes its natural properties. It becomes incorrupt, not spoiling, remaining transparent and fresh for many years. This Holy Water receives the grace to heal illnesses, to drive away demons and every evil power, to preserve people and their dwellings from every danger, to sanctify various objects whether for church or home use. Therefore, Orthodox Christians with reverence drink Holy Water — a great Agiasma (holy thing), as the Greeks call it.
One should always have at home enough Theophany water to last the whole year, and make use of it at every need: in cases of illness, leaving on a journey, whenever one is upset, students prior to examinations, etc. People who drink a little Holy Water daily, before eating any kind of food, do well. It strengthens the powers of our soul—if it is done with prayer and reverence, and one does not merely expect a mechanical result from it.
Reference: From a sermon by Saint John of Shanghai and San Francisco