Narendra Modi may be feeling flush enough to spend millions on putting a loo in every home, but people also need to understand why they should use them

From being the humble recipient of human waste, the toilet has reached the exalted status of being the subject of speeches by India’s Narendra Modi. The prime minister promised to put a toilet in every home by 2019 in his independence day speech in August, and recently reaffirmed a government target to build 5.2m lavatories in the first 100 days of his tenure.

The ministry of drinking water and sanitation has put its money where Modi’s mouth is by substantially raising subsidies for building toilets. Government subsidies for household loos have risen by almost 50%. The amount set aside for community toilets has trebled. There’s more funding for them in schools and health centres, too.

But do these figures add up?

The logic behind the increases is that previous allocations were too small to make toilets that would last. Government subsidies equivalent to £5-12 per household often produced loos that quickly went out of use. Ministry figures show that 77% of households living below the poverty line –those who qualify for government subsidies – have toilets. But as many as four out of 10 of those are thought to be out of order.

These disappointing figures hide a deeper problem.

Over the years, the government has released grant money to build toilets to just under 85% of households living in poverty. But only 40% of those lavatories exist today. So about 35m toilets that were paid for, at least in part, by the government simply do not exist now.

A major fault in the programme lies with the people who are supposed to benefit. Defecating in the open is an unfortunate fact of life for many people in India. An estimated 620 million people – about half of the population – defecate in the open every day.

Yet, using government figures, 490 million people in rural India, of the total rural population of 888 million, have toilets. This implies that there are millions of people defecating in the open despite supposedly having access to a loo.

There is an explanation for this. Studies from different parts of India indicate that the use of toilets, even where they do exist, is low (pdf), at about 35%. That means only about 220 million people in rural India actually use their toilets. Another 270 million do not.

Why is this happening? Part of the problem is the poor quality of the toilets. But another part is the previous programme’s fundamental flaw: only small amounts of money were allocated to promote better hygiene and trigger a change in behaviour. It began as a demand-led campaign, teaching people about the hazards of open defecation, so that they would then presumably demand toilets. But it has become driven by achieving numbers, rather than ensuring that the loos are used.

Modi’s new campaign to end open defecation in the next five years does not address this systemic flaw. This ambitious campaign sets a target of 17m toilets a year for the next five years. But funding for education in hygiene and behavioural change remains a small fraction of the total amount. The danger is this, too, will be driven purely by numbers.

It takes six to eight months to convince a village of the need and usefulness of toilets, according to a study by the World Bank. It takes a lot of time and resources, but leads to better construction and much higher levels of use. Focusing on the importance of hygiene before, during and after the construction of toilets can take a community from realising why they need toilets to demanding and using them.

Most people are aware of subsidies for building toilets and will comply with the letter of the scheme. However, they may not comply with its spirit and fail to use the toilets.

In its current form, this ambitious new attempt to end open defecation may spend the equivalent of £1.6m over five years to create even more unused or ineffective toilets.

• Nitya Jacob is the head of policy at WaterAid India