Another way to meet the financial requirements of the Immigration rules is from rental income.This is classed as nonemployment income & to evidence property rental income you must supply the following information:
Confirmation that the person or the person and their partner jointly own the property for which the rental income is received, through:
(1) A copy of the title deeds of the property or of the title register from the Land Registry (or overseas equivalent); or
(2) A mortgage statement.
(ii) personal bank statements for or from the 12-month period prior to the date of application showing the income relied upon was paid into an account in the name of the person or of the person and their partner jointly.
(iii) A rental agreement or contract.
This is general guidance further information can be found here Appendix FM/SE source.
Further information on how to use cash savings – UK Visa Cash savings