Modern Vastu puts the underground water tank in the north, north-east or east, and the overhead tank in the west or south-west, usually on the roof. The first half has a classical verse behind it: the Brihat Samhita gives a result for water in each of the eight directions, with the north and north-east favoured (53.119). The overhead tank rule is modern. This page explains both, and also what a household needs to do to keep stored water safe, which is the part that affects health.
What the verse says
The Brihat Samhita lists the result of having a piece of water in each direction of the house. Taken in order from the east, the results are given as the loss of sons, danger from fire, trouble from enemies, quarrels among women, unchastity among women, poverty, an increase of wealth and an increase of sons (53.119, Iyer; Sastri has the same sense). The language belongs to its time, and this site does not repeat the results as predictions about anyone.
What the verse offers is a pattern. Water is welcomed in the north and north-east, and cautioned in the south-east, the quarter of fire, and in the south and south-west. That is the origin of the modern habit of putting an underground tank or sump in the north or north-east. The toilets and water page sets out the verse alongside the rules for toilets and gives the wider context.
The overhead tank
The verse is about a reservoir or piece of water in the plan of a house, which was on the ground. It says nothing about a tank on the roof. The modern rule for overhead tanks has a different reasoning: a full tank is heavy, the south-west is the heavy corner, and so the tank goes on the south-west or west part of the roof. Popular guides add that the tank should not be in the north-east, because a heavy load there would weigh down the light corner.
That is a coherent rule and it is also structurally convenient. A concentrated weight is best placed over the strongest part of the building, usually the thick walls of a corner, and a tank on the roof of the south-west column and wall line follows that. It is still convention, and a tank placed elsewhere with a proper support is as safe.
The popular chart
| Item | Modern suggestion | Source |
|---|---|---|
| Underground tank or sump | North, north-east or east | Classical in part (53.119) |
| Overhead tank | West or south-west of the roof | Modern |
| No tank in the south-east | Modern; follows the fire caution in 53.119 | Mixed |
| No tank over the puja room or kitchen | Modern | Hygiene and leaks |
| Overflow pipe to the north or east | Modern | Drains away from the heavy side |
| Tank cover and a clean inlet | Practical | Safety |
The one that mixes sources is the south-east caution. The verse warns that water in the south-east brings danger from fire (53.119), and modern guides keep tanks out of that corner. That follows the verse.
Practical care of tanks
Most health problems from stored water come from neglect, not from position. A short routine does more than any direction.
- Cover. A tight lid on the overhead tank and on the sump, with a mesh over the vent.
- Clean. Empty and scrub tanks at least twice a year, and more often if the water looks cloudy. Use a clean-up service for large tanks.
- Check. Look for cracks, leaks and algae, and for insects or birds that may have got in.
- Float and overflow. Make sure the float valve works and the overflow pipe is not blocked.
- Distance from the septic tank. The underground tank must be kept apart from any sewage tank, soak pit or drain; the safe distance is set by local codes and by the soil.
- Safety. Fix a ladder only where needed and keep the roof door locked to keep children away.
- Testing. If the water is not from a municipal supply, test it periodically at an accredited lab.
The Manasara summary says tanks and ponds were dug in places convenient to the people using them (chapter 9). That is the classical practical test, and it is still the right one: put the tank where it can be reached, cleaned and fed easily.
Rented homes and flats
In an apartment block the tanks belong to the society and sit wherever the builder put them. You cannot change them, and Vastu rules for them do not apply to your flat in any practical way. What you can do is ask for a cleaning schedule and check the water that reaches your tap. Fit a filter at the kitchen tap if you wish. The apartments page explains what carries over in a block.
For a house, if you are building, discuss tank positions with the structural engineer first. If the plan already has a tank in a different place, no text we read asks you to move it.
What cannot be changed, and what helps
If your overhead tank is in the north-east of the roof or your sump is in the south-east, you do not need to demolish anything. Some gentle steps follow.
- Keep the tank and the area round it clean and tidy.
- Have a structural engineer confirm that the roof can bear the load.
- Keep the tank cover closed and the sump covered.
- Check for leaks and repair them quickly, which is the one real risk.
- Keep the north-east of the house light and clear if you wish to follow the modern chart.
See also borewells and wells for the source of the water, septic tanks for the drainage side, and remedies without demolition for the general approach. The room-by-room table shows where water sits in the popular chart.
Frequently asked questions
↳ Where should the underground water tank be in Vastu?
Modern guides say north, north-east or east. The Brihat Samhita gives good results for water in the north and north-east (53.119), which is the classical root of the rule.
↳ Where should the overhead tank go?
Popular guides say west or south-west of the roof, so that the weight sits over the heavy corner. The classical verse is about water in the plan, not roof tanks, so this is a modern convention.
↳ Is a tank in the north-east a problem?
An underground tank there is favoured. A heavy overhead tank there is advised against by modern guides because it loads the light corner. No verse we read forbids it, and a properly supported tank is safe anywhere.
↳ How often should a water tank be cleaned?
At least twice a year is a common recommendation, and more often if the water looks cloudy or smells. Cleaning and a tight cover matter more for health than any direction.
Sources
- Varahamihira, Brihat Samhita, chapter 53, verse 119, in the English translations of Iyer and Sastri.
- Prasanna Kumar Acharya, Summary of the Manasara, chapter 9, for tanks dug in convenient places.
- The overhead tank rule, the overflow rule and the avoidance rules are modern teaching and are not traced to any verse.