Behind the result - No mystery in the method
Base annual allowance = planned visits × allowance per visit + annual supplies + any one-off allowance. Contingency = base × percentage, rounded to cents. Target = base + contingency. Remaining amount = max(0, target − any amount already set aside). The monthly saving target rounds that remaining amount divided by the entered months up to the next cent; the result shows any small rounding surplus. Blank one-off and saved amounts act as zero internally but are omitted from entered-amount lines. Months is a funding period, not a repeat-service frequency. No interest, inflation, financing charge or tax treatment is modelled.
The tool does not fetch live prices, diagnose a hidden sewer problem or book a service. Blank optional fields are omitted. Text is displayed literally, not interpreted as HTML.
The result is a working note. Review it before use; changing an input clears the previous result. A download stays on your device until you delete it. This website cannot assess conditions behind walls or underground.
Before you go
Does this predict the cost of a sewer repair?
No. It organises amounts you choose. Hidden damage, emergency response and actual service costs may differ substantially. Obtain appropriate inspections and written quotes rather than relying on a household allowance.
Is the monthly figure a bill or payment plan?
No. It is your remaining allowance divided by the funding months, rounded upward to cents. No money is collected, no account is opened and no instalment agreement is made.
Why is the sum of monthly targets slightly higher?
Rounding upward to whole cents ensures that the modelled total covers the remaining target. The result displays the small excess. If money already set aside covers the target, the monthly saving figure is zero.
Does a regular allowance mean I should buy drain chemicals?
No. The supplies line is an optional planning choice for non-chemical items such as appropriate visible strainers, not an instruction to use cleaning products. Never mix drain chemicals; professional help is needed for flooding, backups or repeated clogs.