The answer depends what you ...

The answer depends what you mean by "safe".

In the UK all public water supplies are treated in accordance with the Water Supply (Water Quality) regulations. The regulations are based on World Health Organisation (WHO) guidelines which in turn are based on an individual being drink a water all their life without exceed a one-in-a-million risk. This is a very conservative and safe approach.

By comparison, UK bottled water only has to comply with the The Natural Mineral Water, Spring Water and Bottled Drinking Water (England) (Amendment) Regulations 2018. While these are a subset of the WS(WQ) regulations they adress the main microbiological and chemical parameters of public health concern. As such I would not expect it cause harm to fit, healthy individuals, especially if it not consumed regularly.

I would personally be comfortable that supplying bottled water that conforms to the bottled water regulations to a a fit, healthy adult. However, if you are dealing babies, the elderly and infirm, or immuno-compromised individuals you need specialist advice on a case by case basis.

When considering the provision of bottled water you MUST have a clear understanding of its quality AND carry out sufficient checks to ensure that the quality promised is being delivered.

If you do not do this, you and your organisation alone become responsible for any harm done.

As a side note: the Drinking Water Inspectorate in the UK does not allow the provision of supermarket bottled water as an alternative to an interrupted mains supply. Such bottled water has to come from a specialist supplier and be certified by a competent authority as conforming to the DW(SW) regulations.

I hope this is the kind of information that you are looking for, If not, please feel free to get in touch again.