The cheapest way to resolve constipation is still to drink plenty of plain, old-fashioned water, ie, boiled tap water.

An average sized person will need to drink about 1.5 litres (1,500 ml) a day, not all at one go of course, but spread evenly throughout the day. If he/she exercises a lot or does heavy physical work leading to much perspiration, then naturally he would need to drink more than the 1.5 litres to replace the water lost through sweating.