The tide of investor demand stays high for municipal bond mutual funds.

A strong week of record-low muni bond yields on the intermediate and long ends of the curve marked the week ended July 25.

Muni bond funds recorded almost $810 million of inflows from funds that report their flows weekly, according to Lipper FMI. They have seen inflows for 15 consecutive weeks.

Inflow numbers continued to rise from the strong positive flows of the previous week. There were net inflows of $837 million in the week ended July 18. For context, the muni market has now seen positive flows for 44 of the past 47 weeks.

The market saw the most strength in the intermediate portion of the triple-A yield curve. Since last Friday, yields at the intermediate and long ends continued to break record lows. They settled on Thursday close at 1.60% and 2.79%, respectively. Reinvestment money and less volume have ratcheted up investor demand.

Muni yields have outperformed those of Treasuries since last Friday. And though ratios to Treasuries remain in cheap territory, they've gotten richer on the week.

This past week, assets for all muni funds that report their flows weekly leapt to $307.6 billion from $305.3 billion the week before. They've jumped more than $4 billion over the past two weeks.

The value of the holdings for weekly reporting funds rose by $1.55 billion. The week before, they increased by $1.14 billion.

The four-week moving average for all municipal bond mutual funds that report their flows weekly saw a $654 million inflow, rising from a $608 million gain the week before.

Long-term bond funds continued to see impressive flows as well. They represented well more than half of the overall figure for muni bond funds.

Long-term bond funds that report their flows weekly saw inflows to the tune of $504 million, an increase from $464 million the week before.

High-yield muni funds saw strong inflows. In fact, flows have been positive for 18 consecutive weeks, and 32 of the previous 33 weeks.

High-yield funds that report weekly saw $257 million in inflows, Lipper said. The previous week, they reported $288 million in inflows.

Assets for high-yield funds that report their flows weekly increased to $42.62 billion, up from $42.09 billion the previous week.

The value of the holdings for weekly reporting funds rose by $276 million. Last week, they increased by $233 million.

The four-week moving average for all high-yield muni bond funds that report their flows weekly was nearly $215 million of inflows, up from $202 million the week before.