Maybe something like: Flowban.

Thanks Jim Mat. This looks great, the only issue for me is that the water access is behind a tiled wall...though it might come down to having to remove that.

Thanks for the comment Stax but if I remove the faucet handles, it will be inconvenient to put them back on each time I need to run the bath. I was hoping there was some kind of lock that could just go on top, like they do with outdoor taps.

Flow restrictors for showers are very common now, especially in California, but the flow of tub spouts is not required to be restricted. However, many shower heads have flow restrictors that just insert in the fitting where the head screws on, so maybe they could be adapted to be screwed on to a tub spout. This should keep the flow down enough so that the overflow could handle it if the taps are left on.

Bruce

You can get an automatic water shutoff system put in the home. The way it works is that there is an automatic kill valve installed on the water supply to the house, wired to a receiver. You can place wireless sensors all over the home. If a sensor gets wet it kills the water to the entire house. A lot of people who leave their home for extended periods in winter who are worried about burst pipes while they are not home use these systems.

I am not familiar with this particular system, nor do I personally endorse it, this was just one example I could get a link to quickly on Amazon: https://www.amazon.com/Automatic-Shut-Off-Valve-leakSMART-Water/dp/B071YHRXG4

You'd have to shop around to make sure you get a quality product.

I'd also say that if you go this route, you probably want to see how much waterproofing you can do to the bathroom floor so that the amount of water overflowing to trigger the cutoff isn't already going to run into the floor and cause damage.

Although I think that the poster above me missed that your dad is turning the bath water on when no one is there and that he might continue to do this even when someone comes in to bathe him several times a week, I do think they have a point. Is it time for your dad to not be left alone at all? If he is leaving the bath tub running, is he going to leave the stove on next, or forget that he is cooking and start a fire? Or walk away on some errand and get lost? You may want to look for a gerontologist/geriatrician to give him a good evaluation. Sometimes medication reactions, or medical problems are behind these kinds of difficulties and other times the doc can simply give you guidelines for what is needed for your dad's safety after doing an evaluation.

Tapstrap

What kind of controls does the tub have? Here is suggestion to use door knob locks on tub controls - intended to keep children from being able to open doors. I'd look at child safety locks...they also make one that works on lever door handles that might work on that type of faucet handle:

For the faucets pictured, I'd still suggest removing the handles... to once again use the handles does not require putting in screws and/or plastic covers... just slip the knobs over the valve stems.

Flowban is the answer. It is designed just for the problem you are having. However, the only ones I've seen have to be installed in the wall. They may make one that can be surface mounted. Might be worth a phone call to find out.

Thank you so much everyone--these are really helpful and exactly the kind of information and links I needed. Indeed, it may be time for my father to go to assisted living, but he is happiest in his home among all his beloved things and I'm hoping I can at least try to give him a little more time there, with the help of a home aide and some "senior proofing," before he has to move away.

I tried.

@viridiana9 I personally believe it's possible to keep a loved one in their own home for the duration in many cases, if that is where they insist on being. We're doing that for someone who is functionally a paraplegic, so that's extreme nursing care right there, but with the costs of assisted living these days, you could easily pay half that amount for a substantial amount of assistance at home. If family can check on him even once per day in addition to 4-hour shifts of nursing care several times a week, you have it made for the time being. Home Instead is one of the best agencies around in the USA to try for temporary nursing assistance, and another great tip is to advertise for a CNA on Craig's List. We've been doing this nearly 3 years and have our own payroll and tax system set up. It's a lot of work, but it's worth it.

We hired our own for our father's caregivers in our home while we worked. By hiring directly, we were able to give all of the pay to the caregiver, instead of having a substantial portion go to an agency. You can check for a nursing assistant license online, pay your own Social Security and worker's compensation and unemployment tax. We had two caregiver who split the day shifts and sometimes helped on evenings and weekends if one of the three adult children was not able to do their shift. We had a blind, bed-bound, weak very elder to care for, though.

My aunt set my cousin's kitchen on fire when they were trying to keep her at home (with dementia) as long as possible - but they didn't have adequate help.

On the other hand, another elderly aunt found two wonderful people who became long term companions and caregivers to my disabled cousin. She did have the financial resources to pay them well. After her death, my brother took over the responsibility and had one of the caregivers move in, with the other one still coming to spell her.

Thanks for the encouragement about keeping Dad at home...I really want to make it work if possible.

@viridiana9 If you are in the United States, I'll just give you a heads up that "well-paid" can mean something around $15 per hour in some localities. $12 per hour is usually the minimum and is what they could get at a nursing home job. You might be able to get by with less if you live in a very rural area. If you live in a high-cost-of-living area, then you could be looking at going up to a starting salary of $17 or $18 per hour. You'll pay more if you use an agency like Home Instead, but it might be worth it to you if you don't need a lot of help to let them handle payroll, staffing, and taxes. Shifts are usually allotted in a minimum of 4-hour slots whether you hire privately or use an agency. If your dad ever develops any sort of condition where he is nearing end-of-life (within 6 months as verified by two doctors), Hospice care can come regularly free of cost to the family. He might also qualify for veteran's benefits that would pay something toward the cost of an in-home aide.

I appreciate your sharing all this info, @Aglitter, this is really helpful to know for my planning.

I would like to add that when I last had friends who worked in Hospice, they provide adjunct care - visits from PT, OT, and Wound Care, music therapists, social workers, pastoral care workers, and maybe bathing aids. They did not provide basic sitters/nursing assistants. That is also not covered by Medicare. It is all up to family and state Medicaid (if the income is low enough) to pay for basic care. There were a very few onsite Hospice Care homes, though, where everything was covered (I believe). Those are rare. I do not know if Medicare pays for "memory care," which are like locked nursing homes for dementia patients, for more than the 100 days they pay for initial nursing home care. You would need to look into that if that time comes. Last I knew, Medicare paid only for skilled nursing care (where you need an RN or Physical or Occupational Therapy), never for any basic care. And the max was for up to 100 days (they decide when you are well enough to go home and quit paying for it then.)

Remove the drain from the tub and hide it. caregiver can put in a rubber stopper